Aflac (AFL) 10-Q 3 Aug 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 26, 2018
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	AFL
Entity Registrant Name	AFLAC INC
Entity Central Index Key	4,977
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		767,800,258

Consolidated Statements of Earn

Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Net premiums, principally supplemental health insurance		$ 4,706	$ 4,665	$ 9,450	$ 9,303
Net investment income		862	802	1,699	1,596
Realized investment gains (losses):
Other-than-temporary impairment losses realized		(5)		(12)
Other-than-temporary impairment losses			(9)		(19)
Other gains (losses)	[1]	8	(47)	(119)	(177)
Total realized investment gains (losses)		3	(56)	(131)	(196)
Other income (loss)		18	17	36	34
Total revenues		5,589	5,428	11,054	10,737
Benefits and expenses:
Benefits and claims, net		3,031	3,039	6,073	6,091
Acquisition and operating expenses:
Amortization of deferred policy acquisition costs		303	283	617	577
Insurance commissions		338	335	676	664
Insurance and other expenses		732	665	1,463	1,339
Interest expense		54	61	111	122
Total acquisition and operating expenses		1,427	1,344	2,867	2,702
Total benefits and expenses		4,458	4,383	8,940	8,793
Earnings before income taxes		1,131	1,045	2,114	1,944
Income taxes		299	332	564	639
Net earnings		$ 832	$ 713	$ 1,550	$ 1,305
Net earnings per share:
Basic (in dollars per share)		$ 1.08	$ 0.90	$ 2	$ 1.64
Diluted (in dollars per share)		$ 1.07	$ 0.89	$ 1.98	$ 1.62
Weighted-average outstanding common shares used in computing earnings per share (In thousands):
Basic (in shares)		772,949	792,865	775,734	797,536
Diluted (in shares)		777,807	798,695	780,814	803,391
Cash dividends per share		$ 0.26	$ 0.22	$ 0.52	$ 0.43
[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net earnings		$ 832	$ 713	$ 1,550		$ 1,305
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period		(493)	9	332		383
Unrealized gains (losses) on fixed maturity securities:
Unrealized holding gains (losses) on fixed maturity securities during period	[1]	(506)	1,075	(2,233)	[2]	549
Reclassification adjustment for realized (gains) losses on fixed maturity securities included in net earnings	[1]	28	1	26		17
Unrealized gains (losses) on derivatives during period		(2)	(2)	4		1
Pension liability adjustment during period		2	0	0		(2)
Total other comprehensive income (loss) before income taxes		(971)	1,083	(1,871)		948
Income tax expense (benefit) related to items of other comprehensive income (loss)		(138)	314	(469)	[2]	177
Other comprehensive income (loss), net of income taxes	[3]	(833)	769	(1,402)		771
Total comprehensive income (loss)		$ (1)	$ 1,482	$ 148		$ 2,076
[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments.
[2]	Amounts have been corrected to exclude the cumulative effects of changes in accounting principles for financial instruments and the tax effects from tax reform as identified in the rollforward of Accumulated Other Comprehensive Income within the Consolidated Statements of Shareholder’s Equity.
[3]	All amounts in the table above are net of tax.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Securities available for sale, at fair value:
Available for sale, fixed maturity securities	[1]	$ 85,881	[2],[3]	$ 84,313	[4]
Securities held to maturity, at amortized cost:
Held to maturity, fixed maturity securities		31,259		31,430
Equity securities, at fair value:
Equity securities	[1],[5]	1,103
Available for sale securities, equity securities				1,023
Other investments	[6]	5,831		3,402
Cash and cash equivalents		3,847		3,491
Total investments and cash		127,921		123,659
Receivables		892		827
Accrued investment income		769		769
Deferred policy acquisition costs		9,740		9,505
Property and equipment, at cost less accumulated depreciation		448		434
Other	[7]	2,216		2,023
Total assets		141,986		137,217
Policy Liabilities:
Future policy benefits		85,046		81,857
Unpaid policy claims		4,524		4,392
Unearned premiums		5,600		5,959
Other policyholders’ funds		7,140		6,939
Total policy liabilities		102,310		99,147
Income taxes		4,069		4,745
Payables for return of cash collateral on loaned securities		3,712		606
Notes payable		5,315		5,289
Other	[8]	2,780		2,832
Total liabilities		118,186		112,619
Shareholders’ equity:
Common stock of $.10 par value. In thousands: authorized 1,900,000 shares in 2018 and 2017; issued 1,347,061 shares in 2018 and 1,345,762 shares in 2017		135		135
Additional paid-in capital		2,117		2,052
Retained earnings		30,809		29,895
Accumulated other comprehensive income (loss):
Unrealized foreign currency translation gains (losses)		(1,766)		(1,750)
Unrealized gain (losses) on fixed maturity securities	[9],[10]	4,836		5,964
Unrealized gains (losses) on derivatives		(23)		(23)
Pension liability adjustment		(195)		(163)
Treasury stock, at average cost		(12,113)		(11,512)
Total shareholders’ equity		23,800		24,598
Total liabilities and shareholders’ equity		141,986		137,217
Consolidated Entity Excluding Variable Interest Entities (VIE)
Securities available for sale, at fair value:
Available for sale, fixed maturity securities	[11]	80,679		78,804
Securities held to maturity, at amortized cost:
Held to maturity, fixed maturity securities		31,259		31,430
Equity securities, at fair value:
Equity securities	[11]	348
Available for sale securities, equity securities	[11]			270
Variable Interest Entity, Consolidated
Securities available for sale, at fair value:
Available for sale, fixed maturity securities	[11],[12]	5,202		5,509
Equity securities, at fair value:
Equity securities		755
Available for sale securities, equity securities				753
Other investments	[13]	4,586		2,341
Policy Liabilities:
Total liabilities		$ 92		$ 128
[1]	Includes perpetual securities
[2]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[3]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[4]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[5]	Includes perpetual securities ($69 at fair value)
[6]	Includes $4,586 in 2018 and $2,341 in 2017 of loan receivables and limited partnerships from consolidated variable interest entities
[7]	Includes $202 in 2018 and $151 in 2017 of derivatives from consolidated variable interest entities
[8]	Includes $92 in 2018 and $128 in 2017 of derivatives from consolidated variable interest entities
[9]	See Note 1 for discussion of the accounting treatment of tax on amounts recorded in accumulated other comprehensive income pursuant to the Tax Act and for the adoption of accounting guidance on January 1, 2018 related to financial instruments.
[10]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments.
[11]	Includes perpetual securities, see Notes 1 and 3 of the Notes to the Consolidated Financial Statements
[12]	Includes perpetual securities
[13]	Consists of TREs, CMLs, MMLs, and alternative investments in limited partnerships

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Available for sale, fixed maturity securities, amortized cost		$ 78,935	[1],[2]	$ 75,132	[3]
Held to maturity, fixed maturity securities, fair value		$ 37,956		$ 38,072
Common stock, par value (in dollars per share)		$ 0.1		$ 0.1
Common stock, shares authorized (in shares)		1,900,000,000		1,900,000,000
Common stock, shares issued (in shares)		1,347,061,000		1,345,762,000
Asset derivatives		$ 457		$ 331
Liability derivatives		367		474
Variable Interest Entity, Consolidated
Available for sale, fixed maturity securities, amortized cost	[4],[5]	4,492		4,538
Asset derivatives	[6]	202		151
Liability derivatives	[6]	92		128
Consolidated Entity Excluding Variable Interest Entities (VIE)
Available for sale, fixed maturity securities, amortized cost	[5]	74,443		70,594
Held to maturity, fixed maturity securities, fair value		37,956		38,072
Loan Receivables and Limited Partnerships | Variable Interest Entity, Consolidated
Other investments held in unit trust, net of reserves, amortized cost		$ 4,586		$ 2,341
[1]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[2]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[3]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[4]	Includes perpetual securities
[5]	Includes perpetual securities, see Notes 1 and 3 of the Notes to the Consolidated Financial Statements
[6]	Consists entirely of derivatives

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions		Total	Common stock:	Additional paid-in capital:	Retained earnings:	Accumulated other comprehensive income (loss):	Treasury stock:
Balance, beginning of period at Dec. 31, 2016			$ 135	$ 1,908	$ 25,981	$ 2,630	$ (10,172)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options				28
Share-based compensation				24
Treasury stock reissued				20			30
Net earnings		$ 1,305			1,305
Dividends to shareholders					(344)
Unrealized foreign currency translation gains (losses) during period, net of income taxes						403
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments	[1]					368
Unrealized gains (losses) on derivatives during period, net of income taxes						1
Pension liability adjustment during period, net of income taxes						(1)
Purchases of treasury stock							(813)
Balance, end of period at Jun. 30, 2017		21,503	135	1,980	26,942	3,401	(10,955)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2016-01	[1]				0	0
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2018-02	[1]				0	0
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2016-01	[1]				148
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2018-02	[1]				(374)
Balance, beginning of period at Dec. 31, 2017		24,598	135	2,052	29,895	4,028	(11,512)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options				21
Share-based compensation				25
Treasury stock reissued				19			14
Net earnings		1,550			1,550
Dividends to shareholders					(410)
Unrealized foreign currency translation gains (losses) during period, net of income taxes						309
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments	[1]					(1,714)
Unrealized gains (losses) on derivatives during period, net of income taxes						3
Pension liability adjustment during period, net of income taxes						0
Purchases of treasury stock							(615)
Balance, end of period at Jun. 30, 2018		$ 23,800	$ 135	$ 2,117	$ 30,809	$ 2,852	$ (12,113)
[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018.

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net earnings	$ 1,550	$ 1,305
Adjustments to reconcile net earnings to net cash provided by operating activities:
Change in receivables and advance premiums	(1)	8
Capitalization of deferred policy acquisition costs	(716)	(693)
Amortization of deferred policy acquisition costs	617	577
Increase in policy liabilities	1,346	1,326
Change in income tax liabilities	(180)	368
Realized investment (gains) losses	131	196
Other, net	60	78
Net cash provided (used) by operating activities	2,807	3,165
Proceeds from investments sold or matured:
Available-for-sale fixed maturity securities	3,869	2,574
Equity securities, FV-NI	216
Equity securities, available-for-sale		157
Held-to-maturity fixed maturity securities	878	1,311
Other investments - loan receivables	358	90
Costs of investments acquired:
Available for sale fixed maturity securities	(6,798)	(5,662)
Equity securities, FV-NI	(233)
Equity securities, available-for-sale		(178)
Other investments - loan receivables	(2,705)	(492)
Other investments, excluding loan receivables, net	(175)	(112)
Settlement of derivatives, net	(36)	(34)
Cash received (pledged or returned) as collateral, net	3,110	(129)
Other, net	73	(42)
Net cash provided (used) by investing activities	(1,443)	(2,517)
Cash flows from financing activities:
Purchases of treasury stock	(601)	(813)
Proceeds from borrowings	0	524
Principal payments under debt obligations	0	(656)
Dividends paid to shareholders	(396)	(328)
Change in investment-type contracts, net	9	23
Treasury stock reissued	12	17
Other, net	(12)	2
Net cash provided (used) by financing activities	(988)	(1,231)
Effect of exchange rate changes on cash and cash equivalents	(20)	(12)
Net change in cash and cash equivalents	356	(595)
Cash and cash equivalents, beginning of period	3,491	4,859
Cash and cash equivalents, end of period	3,847	4,264
Supplemental disclosures of cash flow information:
Income taxes paid	744	293
Interest paid	90	103
Noncash interest	21	19
Impairment losses included in realized investment losses	12
Impairment losses included in realized investment losses		19
Noncash financing activities:
Capital lease obligations	10	3
Associate stock bonus
Treasury stock issued for:
Treasury stock issued	5	16
Shareholder dividend reinvestment
Treasury stock issued for:
Treasury stock issued	8	16
Share-based compensation grants
Treasury stock issued for:
Treasury stock issued	$ 2	$ 1

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Description of Business Aflac Incorporated (the Parent Company) and its subsidiaries (collectively, the Company) primarily sell supplemental health and life insurance in the United States and Japan. The Company's insurance business is marketed and administered through American Family Life Assurance Company of Columbus (Aflac) in the United States (Aflac U.S.) and, effective April 1, 2018, through Aflac Life Insurance Japan Ltd. in Japan (Aflac Japan). Prior to April 1, 2018, the Company's insurance business was marketed in Japan as a branch of Aflac. American Family Life Assurance Company of New York (Aflac New York) is a wholly owned subsidiary of Aflac. Most of Aflac's policies are individually underwritten and marketed through independent agents. Additionally, Aflac U.S. markets and administers group products through Continental American Insurance Company (CAIC), branded as Aflac Group Insurance. The Company's insurance operations in the United States and Japan service the two markets for the Company's insurance business. Aflac Japan's revenues, including realized gains and losses on its investment portfolio, accounted for 70% and 69% of the Company's total revenues in the six -month periods ended June 30, 2018 and 2017 , respectively. The percentage of the Company's total assets attributable to Aflac Japan was 85% at June 30, 2018 , compared with 83% at December 31, 2017 . Basis of Presentation The Company prepares its financial statements in accordance with U.S. generally accepted accounting principles (GAAP). These principles are established primarily by the Financial Accounting Standards Board (FASB). In these Notes to the Consolidated Financial Statements, references to U.S. GAAP issued by the FASB are derived from the FASB Accounting Standards Codification TM (ASC). The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates based on currently available information when recording transactions resulting from business operations. The most significant items on the Company's balance sheet that involve a greater degree of accounting estimates and actuarial determinations subject to changes in the future are the valuation of investments and derivatives, deferred policy acquisition costs (DAC), liabilities for future policy benefits and unpaid policy claims, and income taxes. These accounting estimates and actuarial determinations are sensitive to market conditions, investment yields, mortality, morbidity, commission and other acquisition expenses, and terminations by policyholders. As additional information becomes available, or actual amounts are determinable, the recorded estimates will be revised and reflected in operating results. Although some variability is inherent in these estimates, the Company believes the amounts provided are adequate. The unaudited consolidated financial statements include the accounts of the Parent Company, its subsidiaries and those entities required to be consolidated under applicable accounting standards. All material intercompany accounts and transactions have been eliminated. In the opinion of management, the accompanying unaudited consolidated financial statements of the Company contain all adjustments, consisting of normal recurring accruals, which are necessary to fairly present the consolidated balance sheets as of June 30, 2018 , and December 31, 2017 , the consolidated statements of earnings and comprehensive income (loss) for the three- and six -month periods ended June 30, 2018 and 2017, and the consolidated statements of shareholders' equity and cash flows for the six -month periods ended June 30, 2018 and 2017 . Results of operations for interim periods are not necessarily indicative of results for the entire year. As a result, these financial statements should be read in conjunction with the financial statements and notes thereto included in the Company's annual report on Form 10-K for the year ended December 31, 2017 ( 2017 Annual Report). Stock split: On February 13, 2018, the Board of Directors of the Parent Company declared a two -for-one stock split of the Company’s common stock in the form of a 100% stock dividend payable on March 16, 2018 to shareholders of record at the close of business on March 2, 2018. The stock split was payable in the form of one additional common stock share for every share of common stock held. All equity and share-based data, including the number of shares outstanding and per share amounts, have been adjusted to reflect the stock split for all periods presented in this Quarterly Report on Form 10-Q. Reclassifications : Certain reclassifications have been made to prior-year amounts to conform to current-year reporting classifications. These reclassifications had no impact on net earnings or total shareholders' equity. Perpetual securities have been reclassified in prior periods from a separate line item to fixed maturity securities to conform to current period reporting classifications. This reclassification had no impact on net earnings or total shareholder’s equity. New Accounting Pronouncements Recently Adopted Accounting Pronouncements Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters Accounting Standards Update (ASU) 2018-03 Technical Corrections and Improvements to Financial Instruments - Overall In February 2018, the FASB issued amendments to clarify certain aspects of the guidance issued in the original Financial Instruments - Overall - Recognition and Measurement pronouncement summarized below. Specifically, for entities who have chosen the measurement alternative approach for equity securities without readily determinable fair values, the amendments clarify that entities may change from a measurement alternative approach to a fair value method through an irrevocable election that would apply to a specific equity security and all identical or similar investments of the same issuer; entities should use an observable price at the date of the transaction rather than reporting date for the measurement alternative calculation; and insurance companies should use a prospective transition method when applying the measurement alternative. The amendments are effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years beginning after June 15, 2018. All entities may early adopt these amendments for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years, as long as they have adopted the Financial Instruments - Overall - Recognition and Measurement guidance discussed below. Early adopted as of January 1, 2018 The adoption of this guidance did not have a significant impact on the Company’s financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2018-02 Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued amendments which allow a reclassification from accumulated other comprehensive income (AOCI) to retained earnings of the effects of the change in the U.S. federal income tax rate resulting from the Tax Cuts and Jobs Act (Tax Act) on the gross deferred tax amounts and the corresponding valuation allowances related to items remaining in AOCI. The amendments eliminate the stranded tax effects resulting from the Tax Act and also require certain disclosures about the reclassified tax effects. The amendments are effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Public business entities may early adopt this guidance in any interim reporting period for which financial statements have not yet been issued. The amendments should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. Early adopted as of January 1, 2018 The amounts reclassified from AOCI to retained earnings include the income tax effects of the change in the federal corporate tax rate enacted by the Tax Act. The Company’s policy is to follow the portfolio approach for releasing income tax effects from AOCI. The adoption of this guidance resulted in an increase to beginning 2018 AOCI of $374 million with a corresponding decrease to beginning 2018 retained earnings as of January 1, 2018. ASU 2017-09 Compensation - Stock Compensation: Scope of Modification Accounting In May 2017, the FASB issued amendments to provide guidance clarifying when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. An entity should apply modification accounting if the fair value, vesting conditions or classification of the award (as an equity instrument or liability instrument) changes as a result of the change in terms or conditions of the award. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-07 Compensation - Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In March 2017, the FASB issued amendments requiring that an employer report the service cost component of net periodic pension cost and net periodic postretirement benefit cost in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net periodic pension cost and net periodic postretirement benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. If a separate line item or items are used to present the other components of net benefit cost, that line item or items must be appropriately described. If a separate line item or items are not used, the line item or items used in the income statement to present the other components of net benefit cost must be disclosed. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2017-05 Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets: Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets In February 2017, the FASB issued amendments that clarify the scope and accounting guidance for the derecognition of a nonfinancial asset or a financial asset that meets the definition of an "in substance nonfinancial asset." The amendments define an "in substance nonfinancial asset" and provide additional accounting guidance for partial sales of nonfinancial assets. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-01 Business Combinations: Clarifying the Definition of a Business In January 2017, the FASB issued amendments clarifying when a set of assets and activities is a business. The amendments provide a screen to exclude transactions where substantially all the fair value of the transferred set is concentrated in a single asset, or group of similar assets, from being evaluated as a business. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-18 Statement of Cash Flows: Restricted Cash In November 2016, the FASB issued amendments requiring that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, statements of cash flows, or disclosures. ASU 2016-16 Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued amendments that require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-15 Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued amendments that provide guidance on eight specific statement of cash flows classification issues. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, statements of cash flows, or disclosures. ASU 2016-01 Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued guidance to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. The main provisions of this guidance require certain equity investments to be measured at fair value with changes in fair value recognized in net earnings; separate presentation in other comprehensive income for changes in fair value of financial liabilities measured under the fair value option that are due to instrument-specific credit risk; and changes in disclosures associated with the fair value of financial instruments. The guidance also clarifies that entities should evaluate the need for a valuation allowance on a deferred tax asset (DTA) related to available-for-sale (AFS) securities in combination with the entity's other DTAs. January 1, 2018 The Company recorded a cumulative effect adjustment with an increase to beginning 2018 retained earnings and a decrease to beginning 2018 AOCI of $148 million, net of taxes. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2014-09 Revenue from Contracts with Customers In May 2014, the FASB issued updated guidance that affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards (e.g., insurance contracts or lease contracts). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. Accounting Pronouncements Pending Adoption Standard Description Effect on Financial Statements or Other Significant Matters ASU 2018-10 Codification Improvements to Topic 842, Leases In July 2018, the FASB issued guidance which clarifies, corrects errors in, or makes minor improvements to the Codification related to ASU 2016-02, Leases (Topic 842). The amendments in this ASU affect narrow aspects of the guidance issued in the amendments to ASU 2016-02, including but not limited to, Residual Value Guarantees, Rate Implicit in the Lease, Lessee Reassessment of Lease Classification and Variable Lease Payments that Depend on an Index or a Rate. Amendments within this ASU follow the effective dates of Topic 842, which are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The adoption of this guidance is not expected to have a significant impact on the Company’s financial position, results of operations, or disclosures. ASU 2018-01 Leases: Land Easement Practical Expedient for Transition to Topic 842 In January 2018, the FASB issued guidance which provides an entity with the option to elect a transition practical expedient to not evaluate, under Topic 842, land easements that exist or expired before the entity's adoption of Topic 842 and that were not previously accounted for as leases under Topic 840. The amendments clarify that new or modified land easements should be evaluated under the new leases standard once an entity has adopted the new standard. The amendments are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-12 Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities In August 2017, the FASB issued guidance which improves and simplifies the accounting rules around hedge accounting and will create more transparency around how economic results are presented on financial statements. Issues addressed in this new guidance include: 1) risk component hedging, 2) accounting for the hedged item in fair value hedges of interest rate risk, 3) recognition and presentation of the effects of hedging instruments, and 4) amounts excluded from the assessment of hedge effectiveness. The amendments are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted in any interim period after issuance of the guidance. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Effect on Financial Statements or Other Significant Matters ASU 2017-08 Receivables - Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued amendments to shorten the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount. The amendments are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-04 Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued amendments simplifying the subsequent measurement of goodwill. An entity, under this update, is no longer required to perform a hypothetical purchase price allocation to measure goodwill impairment. Instead, the entity should perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. The amendments are effective for public business entities that are SEC filers for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for any goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-13 Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued amendments that require a financial asset (or a group of financial assets) measured on an amortized cost basis to be presented net of an allowance for credit losses in order to reflect the amount expected to be collected on the financial asset(s). The measurement of expected credit losses is amended by replacing the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform about a credit loss. Credit losses on available-for-sale debt securities will continue to be measured in a manner similar to current U.S. GAAP; however, the amendments require that credit losses be presented as an allowance rather than as a write-down. Other amendments include changes to the balance sheet presentation and interest income recognition of purchased financial assets with a more-than-insignificant amount of credit deterioration since origination (PCD financial assets). The amendments are effective for public companies for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Companies may early adopt this guidance as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The amendments will be adopted following a modified-retrospective approach resulting in a cumulative effect adjustment in retained earnings as of the beginning of the year of adoption. Two exceptions to this adoption method are for PCD financial assets and debt securities for which other-than-temporary impairment (OTTI) will have been recognized before the effective date. Loans purchased with credit deterioration accounted for under current U.S. GAAP as "purchased credit impaired" (PCI) financial assets will be classified as PCD financial assets at transition and PCD guidance will be applied prospectively. Debt securities that have experienced OTTI before the effective date will follow a prospective adoption method which allows an entity to maintain the same amortized cost basis before and after the effective date. The Company has identified certain financial instruments in scope of this guidance to include certain fixed maturity securities, loan and loan receivables and reinsurance recoverables (See Notes 3 and 7 for current balances of instruments in scope). The Company is continuing its progress towards updating its credit loss projection models and accounting systems in order to comply with the required changes in measurement of credit losses. The Company currently expects loans and loan receivables and held-to-maturity fixed maturity securities to be the asset classes most significantly impacted upon adoption of the guidance. The Company continues to evaluate the impact of adoption of this guidance on its financial position, results of operations, and disclosures. Standard Description Effect on Financial Statements or Other Significant Matters ASU 2016-02 Leases In February 2016, the FASB issued updated guidance for accounting for leases. Per the amendments, lessees will be required to recognize all leases on the balance sheet with the exception of short-term leases. A lease liability will be recorded for the obligation of a lessee to make lease payments arising from a lease. A right-of-use asset will be recorded which represents the lessee’s right to control the use of a specified asset for a lease term. Under the new guidance, lessor accounting is largely unchanged. The amendments are effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company has identified certain operating leases in scope of this guidance to include office space and equipment leases (See Note 15 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report for current balances of leases in scope). The leases within scope of this guidance will increase the Company's right-of-use assets and lease liabilities recorded on its statement of financial position, however the Company estimates leases within scope of the guidance to represent less than 1% of its total assets as of June 30, 2018. The Company estimates that the adoption of this guidance will not have a significant impact on its financial position, results of operations, or disclosures. Recent accounting guidance not discussed above is not applicable, did not have, or is not expected to have a material impact to the Company's business. For additional information on new accounting pronouncements and recent accounting guidance and their impact, if any, on the Company's financial position or results of operations, see Note 1 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report.

BUSINESS SEGMENT INFORMATION

BUSINESS SEGMENT INFORMATION	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
BUSINESS SEGMENT INFORMATION	BUSINESS SEGMENT INFORMATION The Company consists of two reportable insurance business segments: Aflac Japan and Aflac U.S., both of which sell supplemental health and life insurance. Operating business segments that are not individually reportable and business activities, including reinsurance retrocession activities, not included in Aflac Japan or Aflac U.S. are included in the "Corporate and other" category. The Company does not allocate corporate overhead expenses to business segments. Consistent with U.S. GAAP accounting guidance for segment reporting, the Company evaluates and manages its business segments using a financial performance measure called pretax adjusted earnings. Adjusted earnings are adjusted revenues less benefits and adjusted expenses. The adjustments to both revenues and expenses account for certain items that cannot be predicted or that are outside management’s control. Adjusted revenues are U.S. GAAP total revenues excluding realized investment gains and losses, except for amortized hedge costs related to foreign currency denominated investments. Adjusted expenses are U.S. GAAP total acquisition and operating expenses including the impact of interest cash flows from derivatives associated with notes payable but excluding any nonrecurring or other items not associated with the normal course of the Company’s insurance operations and that do not reflect Aflac’s underlying business performance. The Company excludes income taxes related to operations to arrive at pretax adjusted earnings. Information regarding operations by segment follows: Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Revenues: Aflac Japan: Net earned premiums $ 3,227 $ 3,222 $ 6,490 $ 6,416 Net investment income, less amortized hedge costs (1) 606 557 1,194 1,115 Other income 11 10 22 20 Total Aflac Japan 3,844 3,789 7,706 7,551 Aflac U.S.: Net earned premiums 1,426 1,388 2,853 2,778 Net investment income 182 180 357 358 Other income 2 2 4 3 Total Aflac U.S. 1,610 1,570 3,214 3,139 Corporate and other (2) 85 70 164 138 Total adjusted revenues 5,539 5,429 11,084 10,828 Realized investment gains (losses) (1),(2) 50 (1 ) (30 ) (91 ) Total revenues $ 5,589 $ 5,428 $ 11,054 $ 10,737 (1) Amortized hedge costs related to hedging U.S. dollar-denominated investments held in Aflac Japan were $55 and $56 for the three- month periods and $110 and $108 for the six -month periods ended June 30, 2018 , and 2017 , respectively, and have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing segment operations. (2) Amortized hedge costs in Aflac Japan were partially offset by derivatives entered into as part of corporate activities and resulted in a benefit of $7 for the three-month period and $9 for the six -month period ended June 30, 2018 , respectively, which has been reclassified from realized investment gains (losses) and reported as an increase in net investment income when analyzing operations. Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Pretax earnings: Aflac Japan (1) $ 836 $ 791 $ 1,654 $ 1,560 Aflac U.S. 340 330 677 640 Corporate and other (2) (38 ) (48 ) (84 ) (100 ) Pretax adjusted earnings 1,138 1,073 2,247 2,100 Realized investment gains (losses) (1),(2),(3) 35 (19 ) (63 ) (128 ) Other income (loss) (42 ) (9 ) (70 ) (28 ) Total earnings before income taxes $ 1,131 $ 1,045 $ 2,114 $ 1,944 Income taxes applicable to pretax adjusted earnings $ 303 $ 342 $ 592 $ 694 Effect of foreign currency translation on after-tax 7 (9 ) 29 (3 ) (1) Amortized hedge costs related to hedging U.S. dollar-denominated investments held in Aflac Japan were $55 and $56 for the three- month periods and $110 and $108 for the six -month periods ended June 30, 2018 , and 2017 , respectively, and have been reclassified from realized investment gains (losses) and reported as a deduction from pretax adjusted earnings when analyzing segment operations. (2) Amortized hedge costs in Aflac Japan were partially offset by derivatives entered into as part of corporate activities and resulted in a benefit of $7 for the three-month period and $9 for the six -month period ended June 30, 2018 which has been reclassified from realized investment gains (losses) and reported as an increase in pretax adjusted earnings when analyzing operations. (3) Excluding a gain of $17 and $20 for the three-month periods and $33 and $41 for the six -month periods ended June 30, 2018 , and 2017 , respectively, related to the interest rate component of the change in fair value of foreign currency swaps on notes payable which is included in adjusted earnings when analyzing segment operations Assets were as follows: (In millions) June 30, December 31, Assets: Aflac Japan $ 120,228 $ 114,402 Aflac U.S. 19,588 19,893 Corporate and other 2,170 2,922 Total assets $ 141,986 $ 137,217

INVESTMENTS

INVESTMENTS	6 Months Ended
	Jun. 30, 2018
Investments [Abstract]
INVESTMENTS	INVESTMENTS Investment Holdings The amortized cost for the Company's investments in debt securities, the cost for equity securities and the fair values of these investments are shown in the following tables. June 30, 2018 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value Fixed maturity securities: (1) Yen-denominated: Japan government and agencies $ 31,384 $ 3,742 $ 150 $ 34,976 Municipalities 375 32 9 398 Mortgage- and asset-backed securities 156 22 0 178 Public utilities 1,663 313 3 1,973 Sovereign and supranational 1,263 188 30 1,421 Banks/financial institutions 5,399 651 126 5,924 Other corporate 4,298 688 6 4,980 Total yen-denominated 44,538 5,636 324 49,850 U.S. dollar-denominated: U.S. government and agencies 133 8 1 140 Municipalities 1,396 135 1 1,530 Mortgage- and asset-backed securities 162 8 1 169 Public utilities 4,939 555 103 5,391 Sovereign and supranational 264 58 0 322 Banks/financial institutions 2,871 417 30 3,258 Other corporate 24,632 1,569 980 25,221 Total U.S. dollar-denominated 34,397 2,750 1,116 36,031 Total securities available for sale $ 78,935 (1) $ 8,386 $ 1,440 $ 85,881 (1) (1) Includes perpetual securities ( $1,446 at amortized cost and $1,612 at fair value) June 30, 2018 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 21,808 $ 5,409 $ 0 $ 27,217 Municipalities 363 111 0 474 Mortgage- and asset-backed securities 16 1 0 17 Public utilities 3,236 317 1 3,552 Sovereign and supranational 1,557 286 0 1,843 Banks/financial institutions 1,532 178 10 1,700 Other corporate 2,747 406 0 3,153 Total yen-denominated 31,259 6,708 11 37,956 Total securities held to maturity $ 31,259 $ 6,708 $ 11 $ 37,956 June 30, 2018 (In millions) Fair Equity securities, carried at fair value through net earnings: Equity securities: (1) Yen-denominated $ 712 U.S. dollar-denominated 391 Total equity securities $ 1,103 (1) (1) Includes perpetual securities ( $69 at fair value) December 31, 2017 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value: Fixed maturity securities: (1) Yen-denominated: Japan government and agencies $ 27,980 $ 3,363 $ 271 $ 31,072 Municipalities 314 28 12 330 Mortgage- and asset-backed securities 242 29 0 271 Public utilities 1,635 352 6 1,981 Sovereign and supranational 1,380 190 1 1,569 Banks/financial institutions 4,742 811 53 5,500 Other corporate 4,085 809 7 4,887 Total yen-denominated 40,378 5,582 350 45,610 U.S dollar-denominated: U.S. government and agencies 146 13 1 158 Municipalities 872 168 0 1,040 Mortgage- and asset-backed securities 161 12 0 173 Public utilities 5,116 884 27 5,973 Sovereign and supranational 267 73 0 340 Banks/financial institutions 2,808 633 8 3,433 Other corporate 25,384 2,620 418 27,586 Total U.S. dollar-denominated 34,754 4,403 454 38,703 Total securities available for sale $ 75,132 (1) $ 9,985 $ 804 $ 84,313 (1) (1) Includes perpetual securities ( $1,462 at amortized cost and $1,789 at fair value) December 31, 2017 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 21,331 $ 5,160 $ 0 $ 26,491 Municipalities 357 105 0 462 Mortgage- and asset-backed securities 26 1 0 27 Public utilities 3,300 398 0 3,698 Sovereign and supranational 1,523 312 0 1,835 Banks/financial institutions 2,206 190 9 2,387 Other corporate 2,687 485 0 3,172 Total yen-denominated 31,430 6,651 9 38,072 Total securities held to maturity $ 31,430 $ 6,651 $ 9 $ 38,072 December 31, 2017 (In millions) Fair Equity securities, carried at fair value: Equity securities: Yen-denominated $ 695 U.S. dollar-denominated 328 Total equity securities $ 1,023 The methods of determining the fair values of the Company's investments in fixed maturity securities and equity securities are described in Note 5. During the first and second quarters of 2018, the Company did not reclassify any investments from the held-to-maturity category to the available-for-sale category. During the second quarter of 2017, the Company reclassified three investments from the held-to-maturity category to the available-for-sale category as a result of the issuers' credit rating being downgraded to below investment grade. At the time of the transfer, the securities had an amortized cost of $773 million and an unrealized gain of $47 million . During the first quarter of 2017, the Company did not reclassify any investments from the held-to-maturity category to the available-for-sale category. Contractual and Economic Maturities The contractual and economic maturities of the Company's investments in fixed maturity securities at June 30, 2018 , were as follows: (In millions) Amortized Fair Available for sale: (1) Due in one year or less $ 348 $ 359 Due after one year through five years 3,910 4,070 Due after five years through 10 years 11,813 11,912 Due after 10 years 62,547 69,193 Mortgage- and asset-backed securities 317 347 Total fixed maturity securities available for sale $ 78,935 $ 85,881 Held to maturity: Due in one year or less $ 498 $ 505 Due after one year through five years 353 366 Due after five years through 10 years 1,585 1,715 Due after 10 years 28,807 35,353 Mortgage- and asset-backed securities 16 17 Total fixed maturity securities held to maturity $ 31,259 $ 37,956 (1) Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument) Expected maturities may differ from contractual maturities because some issuers have the right to call or prepay obligations with or without call or prepayment penalties. Investment Concentrations The Company's process for investing in credit-related investments begins with an independent approach to underwriting each issuer's fundamental credit quality. The Company evaluates independently those factors that it believes could influence an issuer's ability to make payments under the contractual terms of the Company's instruments. This includes a thorough analysis of a variety of items including the issuer's country of domicile (including political, legal, and financial considerations); the industry in which the issuer competes (with an analysis of industry structure, end-market dynamics, and regulation); company specific issues (such as management, assets, earnings, cash generation, and capital needs); and contractual provisions of the instrument (such as financial covenants and position in the capital structure). The Company further evaluates the investment considering broad business and portfolio management objectives, including asset/liability needs, portfolio diversification, and expected income. Investment exposures that individually exceeded 10% of shareholders' equity were as follows: June 30, 2018 December 31, 2017 (In millions) Credit Amortized Fair Credit Amortized Fair Japan National Government (1) A+ $51,881 $60,734 A $48,399 $56,532 (1) Japan Government Bonds (JGBs) or JGB-backed securities Realized Investment Gains and Losses Information regarding pretax realized gains and losses from investments is as follows: Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Realized investment gains (losses): Fixed maturity securities: (1) Available for sale: Gross gains from sales $ 12 $ 10 $ 22 $ 22 Gross losses from sales (71 ) (8 ) (73 ) (19 ) Foreign exchange gains (losses) 29 (18 ) 24 (50 ) Other-than-temporary impairment losses (2 ) (1 ) (2 ) (4 ) Total fixed maturity securities (32 ) (17 ) (29 ) (51 ) Equity securities (1),(2) 18 15 (3) (28 ) 34 (3) Loan loss reserves (3 ) (2 ) (10 ) (3 ) Derivatives and other: Derivative gains (losses) (172 ) (51 ) (28 ) (103 ) Foreign currency gains (losses) 192 (1 ) (36 ) (73 ) Total derivatives and other 20 (52 ) (64 ) (176 ) Total realized investment gains (losses) $ 3 $ (56 ) $ (131 ) $ (196 ) (1) Includes perpetual securities (2) See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments. (3) Includes impairments of $6 for the three-month period and $12 for the six-month period ended June 30, 2017 The unrealized holding gains, net of losses, recorded as a component of realized investment gains and losses for the three-month period ended June 30, 2018, that relates to equity securities still held at the June 30, 2018, reporting date was $19 million . The unrealized holding losses, net of gains, recorded as a component of realized investment gains and losses for the six-month period ended June 30, 2018, that relates to equity securities still held at the June 30, 2018, reporting date was $24 million . Unrealized Investment Gains and Losses Effect on Shareholders’ Equity The net effect on shareholders’ equity of unrealized gains and losses from investment securities was as follows: (In millions) June 30, 2018 December 31, Unrealized gains (losses) on securities available for sale $ 6,946 $ 9,358 Deferred income taxes (2,110 ) (3,394 ) Shareholders’ equity, unrealized gains (losses) on investment securities $ 4,836 $ 5,964 See Note 1 for discussion of the accounting treatment of tax on amounts recorded in accumulated other comprehensive income pursuant to the Tax Act and for the adoption of accounting guidance on January 1, 2018 related to financial instruments. Gross Unrealized Loss Aging The following tables show the fair values and gross unrealized losses of the Company's available-for-sale and held-to-maturity investments that were in an unrealized loss position, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position. June 30, 2018 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: (1) U.S. government and U.S. dollar-denominated $ 78 $ 1 $ 74 $ 1 $ 4 $ 0 Japan government and Yen-denominated 3,647 150 0 0 3,647 150 Municipalities: U.S. dollar-denominated 261 1 261 1 0 0 Yen-denominated 137 9 13 0 124 9 Mortgage- and asset- U.S. dollar-denominated 86 1 71 1 15 0 Public utilities: U.S. dollar-denominated 1,664 103 1,200 52 464 51 Yen-denominated 268 4 180 1 88 3 Sovereign and supranational: U.S. dollar-denominated 13 0 13 0 0 0 Yen-denominated 286 30 286 30 0 0 Banks/financial institutions: U.S. dollar-denominated 696 30 561 20 135 10 Yen-denominated 2,344 136 1,478 50 866 86 Other corporate: U.S. dollar-denominated 13,044 980 8,391 362 4,653 618 Yen-denominated 409 6 294 4 115 2 Total $ 22,933 $ 1,451 $ 12,822 $ 522 $ 10,111 $ 929 (1) Includes perpetual securities December 31, 2017 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: (1) U.S. government and U.S. dollar-denominated $ 74 $ 1 $ 74 $ 1 $ 0 $ 0 Japan government and Yen-denominated 5,255 271 1,264 9 3,991 262 Municipalities: Yen-denominated 129 12 10 0 119 12 Public utilities: U.S. dollar-denominated 785 27 221 3 564 24 Yen-denominated 83 6 0 0 83 6 Sovereign and supranational: Yen-denominated 309 1 309 1 0 0 Banks/financial institutions: U.S. dollar-denominated 362 8 316 5 46 3 Yen-denominated 1,507 62 394 4 1,113 58 Other corporate: U.S. dollar-denominated 7,741 418 2,839 50 4,902 368 Yen-denominated 440 7 349 4 91 3 Total $ 16,685 $ 813 $ 5,776 $ 77 $ 10,909 $ 736 (1) Includes perpetual securities Analysis of Securities in Unrealized Loss Positions The unrealized losses on the Company's fixed maturity securities investments have been primarily related to general market changes in interest rates, foreign exchange rates, and/or the levels of credit spreads rather than specific concerns with the issuer's ability to pay interest and repay principal. For any significant declines in fair value of its fixed maturity securities, the Company performs a more focused review of the related issuers' credit profile. For corporate issuers, the Company evaluates their assets, business profile including industry dynamics and competitive positioning, financial statements and other available financial data. For non-corporate issuers, the Company analyzes all sources of credit support, including issuer-specific factors. The Company utilizes information available in the public domain and, for certain private placement issuers, from consultations with the issuers directly. The Company also considers ratings from Nationally Recognized Statistical Rating Organizations (NRSROs), as well as the specific characteristics of the security it owns including seniority in the issuer's capital structure, covenant protections, or other relevant features. From these reviews, the Company evaluates the issuers' continued ability to service the Company's investment through payment of interest and principal. Assuming no credit-related factors develop, unrealized gains and losses on fixed maturity securities are expected to diminish as investments near maturity. Based on its credit analysis, the Company believes that the issuers of its fixed maturity investments in the sectors shown in the table above have the ability to service their obligations to the Company. Other Investments The table below reflects the composition of the carrying value for other investments as of the periods presented. (In millions) June 30, 2018 December 31, 2017 Other investments: Transitional real estate loans $ 3,247 $ 1,235 Commercial mortgage loans 966 908 Middle market loans 1,097 859 Policy loans 222 210 Short-term investments 1 57 Other 298 133 Total other investments $ 5,831 $ 3,402 Loans and Loan Receivables The Company classifies its transitional real estate loans (TREs), commercial mortgage loans (CMLs) and middle market loans (MMLs) as held-for-investment and includes them in the other investments line on the consolidated balance sheets. The Company carries them on the balance sheet at amortized cost less an estimated allowance for loan losses. The Company's allowance for loan losses is established using both general and specific allowances. The general allowance is used for loans grouped by similar risk characteristics where a loan-specific or market-specific risk has not been identified, but for which the Company estimates probable incurred losses. The specific allowance is used on an individual loan basis when it is probable that a loss has been incurred. As of June 30, 2018 , and December 31, 2017 , the Company's allowance for loan losses was $21 million and $11 million , respectively. As of June 30, 2018 , and December 31, 2017 , the Company had no loans that were past due in regards to principal and/or interest payments. Additionally, the Company held no loans that were on nonaccrual status or considered impaired as of June 30, 2018 , and December 31, 2017 . The Company had no troubled debt restructurings during the six months ended June 30, 2018 and 2017. Transitional Real Estate Loans Transitional real estate loans are commercial mortgage loans that are typically relatively short-term floating rate instruments secured by a first lien on the property. These loans provide funding for properties undergoing a change in their physical characteristics and/or economic profile. As of June 30, 2018 , the Company had $1.2 billion in outstanding commitments to fund transitional real estate loans. These commitments are contingent on the final underwriting and due diligence to be performed. Commercial Mortgage Loans As of June 30, 2018 , the Company had $79 million in outstanding commitments to fund commercial mortgage loans. These commitments are contingent on the final underwriting and due diligence to be performed. Middle Market Loans Middle market loans are generally considered to be below investment grade. The carrying value for middle market loans included an unfunded amount of $90 million and $109 million , as of June 30, 2018 , and December 31, 2017 , respectively, that is reflected in other liabilities on the consolidated balance sheets. As of June 30, 2018 , the Company had commitments of approximately $774 million to fund potential future loan originations related to this investment program. These commitments are contingent upon the availability of middle market loans that meet the Company's underwriting criteria. Other Other investments primarily includes investments in limited partnerships. As of June 30, 2018 , the Company had $1.1 billion in outstanding commitments to fund alternative investments in limited partnerships. Variable Interest Entities (VIEs) As a condition of its involvement or investment in a VIE, the Company enters into certain protective rights and covenants that preclude changes in the structure of the VIE that would alter the creditworthiness of the Company's investment or its beneficial interest in the VIE. For those VIEs other than certain unit trust structures, the Company's involvement is passive in nature. The Company has not, nor has it been, required to purchase any securities issued in the future by these VIEs. The Company's ownership interest in VIEs is limited to holding the obligations issued by them. The Company has no direct or contingent obligations to fund the limited activities of these VIEs, nor does it have any direct or indirect financial guarantees related to the limited activities of these VIEs. The Company has not provided any assistance or any other type of financing support to any of the VIEs it invests in, nor does it have any intention to do so in the future. For those VIEs in which the Company holds debt obligations, the weighted-average lives of the Company's notes are very similar to the underlying collateral held by these VIEs where applicable. The Company's risk of loss related to its interests in any of its VIEs is limited to the carrying value of the related investments held in the VIE. VIEs - Consolidated The following table presents the cost or amortized cost, fair value and balance sheet caption in which the assets and liabilities of consolidated VIEs are reported. Investments in Consolidated Variable Interest Entities June 30, 2018 December 31, 2017 (In millions) Cost or Amortized Fair Cost or Amortized Fair Assets: Fixed maturity securities, available for sale (1) $ 4,492 $ 5,202 $ 4,538 $ 5,509 Equity securities 755 755 606 753 Other investments (2) 4,586 4,577 2,341 2,328 Other assets (3) 202 202 151 151 Total assets of consolidated VIEs $ 10,035 $ 10,736 $ 7,636 $ 8,741 Liabilities: Other liabilities (3) $ 92 $ 92 $ 128 $ 128 Total liabilities of consolidated VIEs $ 92 $ 92 $ 128 $ 128 (1) Includes perpetual securities (2) Consists of TREs, CMLs, MMLs, and alternative investments in limited partnerships (3) Consists entirely of derivatives The Company is substantively the only investor in the consolidated VIEs listed in the table above. As the sole investor in these VIEs, the Company has the power to direct the activities of a variable interest entity that most significantly impact the entity's economic performance and is therefore considered to be the primary beneficiary of the VIEs that it consolidates. The Company also participates in substantially all of the variability created by these VIEs. The activities of these VIEs are limited to holding invested assets and foreign currency, and/or credit default swaps (CDS), as appropriate, and utilizing the cash flows from these securities to service its investment. Neither the Company nor any of its creditors are able to obtain the underlying collateral of the VIEs unless there is an event of default or other specified event. For those VIEs that contain a swap, the Company is not a direct counterparty to the swap contracts and has no control over them. The Company's loss exposure to these VIEs is limited to its original investment. The Company's consolidated VIEs do not rely on outside or ongoing sources of funding to support their activities beyond the underlying collateral and swap contracts, if applicable. With the exception of its investment in unit trust structures, the underlying collateral assets and funding of the Company's consolidated VIEs are generally static in nature and the underlying collateral and the reference corporate entities covered by any CDS contracts were all investment grade at the time of issuance. Investments in Unit Trust Structures The Company also utilizes unit trust structures in its Aflac Japan segment to invest in various asset classes. As the sole investor of these VIEs, the Company is required to consolidate these trusts under U.S. GAAP. VIEs-Not Consolidated The table below reflects the amortized cost, fair value and balance sheet caption in which the Company's investment in VIEs not consolidated are reported. Investments in Variable Interest Entities Not Consolidated June 30, 2018 December 31, 2017 (In millions) Amortized Fair Amortized Fair Assets: Fixed maturity securities, available for sale (1) $ 4,870 $ 5,358 $ 5,004 $ 5,724 Fixed maturity securities, held to maturity 2,469 2,795 2,549 2,929 Other investments 106 106 55 55 Total investments in VIEs not consolidated $ 7,445 $ 8,259 $ 7,608 $ 8,708 (1) Includes perpetual securities The Company holds alternative investments in limited partnerships that have been determined to be VIEs. These partnerships invest in private equity and structured investments. The Company’s maximum exposure to loss on these investments is limited to the amount of its investment. The Company is not the primary beneficiary of these VIEs and is therefore not required to consolidate them. The Company classifies these investments as Other investments in the consolidated balance sheets. Certain investments in VIEs that the Company is not required to consolidate are investments that are in the form of debt obligations from the VIEs that are irrevocably and unconditionally guaranteed by their corporate parents or sponsors. These VIEs are the primary financing vehicles used by their corporate sponsors to raise financing in the capital markets. The variable interests created by these VIEs are principally or solely a result of the debt instruments issued by them. The Company does not have the power to direct the activities that most significantly impact the entity's economic performance, nor does it have the obligation to absorb losses of the entity or the right to receive benefits from the entity. As such, the Company is not the primary beneficiary of these VIEs and is therefore not required to consolidate them. Securities Lending and Pledged Securities The Company lends fixed maturity and public equity securities to financial institutions in short-term security-lending transactions. These short-term security-lending arrangements increase investment income with minimal risk. The Company's security lending policy requires that the fair value of the securities and/or unrestricted cash received as collateral be 102% or more of the fair value of the loaned securities. These securities continue to be carried as investment assets on the Company's balance sheet during the terms of the loans and are not reported as sales. The Company receives cash or other securities as collateral for such loans. For loans involving unrestricted cash or securities as collateral, the collateral is reported as an asset with a corresponding liability for the return of the collateral. Details of the Company's securities lending activities were as follows: Securities Lending Transactions Accounted for as Secured Borrowings June 30, 2018 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 30-90 days Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 2,942 353 $ 3,295 Public utilities 13 0 0 13 Banks/financial institutions 60 0 0 60 Other corporate 335 0 0 335 Equity securities 9 0 0 9 Total borrowings $ 417 $ 2,942 $ 353 $ 3,712 Gross amount of recognized liabilities for securities lending transactions $ 3,712 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 0 (1) These securities are pledged as collateral under the Company's U.S. securities lending program and can be called at its discretion; therefore, they are classified as Overnight and Continuous. Securities Lending Transactions Accounted for as Secured Borrowings December 31, 2017 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 49 $ 49 Public utilities 73 0 73 Banks/financial institutions 54 0 54 Other corporate 415 0 415 Equity securities 15 0 15 Total borrowings $ 557 $ 49 $ 606 Gross amount of recognized liabilities for securities lending transactions $ 606 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 0 (1) These securities are pledged as collateral under the Company's U.S. securities lending program and can be called at its discretion; therefore, they are classified as Overnight and Continuous. The Company did not have any repurchase agreements or repurchase-to-maturity transactions outstanding as of June 30, 2018 , and December 31, 2017 , respectively. Certain fixed maturity securities can be pledged as collateral as part of derivative transactions, or pledged to support state deposit requirements or certain investment programs. For additional information regarding pledged securities related to derivative transactions, see Note 4.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS	DERIVATIVE INSTRUMENTS The Company's freestanding derivative financial instruments have historically consisted of: (1) foreign currency forwards and options used in hedging foreign exchange risk on U.S. dollar-denominated investments in Aflac Japan's portfolio; (2) foreign currency forwards and options used to economically hedge certain portions of forecasted cash flows denominated in yen and hedge the Company's long term exposure to a weakening yen; (3) swaps associated with the Company's notes payable, consisting of cross-currency interest rate swaps, also referred to as foreign currency swaps, associated with certain senior notes and its subordinated debentures; and (4) foreign currency swaps and credit default swaps that are associated with investments in special-purpose entities, including VIEs where the Company is the primary beneficiary. The Company does not use derivative financial instruments for trading purposes, nor does it engage in leveraged derivative transactions. Some of the Company's derivatives are designated as cash flow hedges, fair value hedges or net investment hedges; however, other derivatives do not qualify for hedge accounting or the Company elects not to designate them as accounting hedges. Derivative Types Foreign currency forwards and options are executed for the Aflac Japan segment in order to hedge the currency risk on the carrying value of certain U.S. dollar-denominated investments. The average maturity of these forwards and options can change depending on factors such as market conditions and types of investments being held. In situations where the maturity of the forwards and options are shorter than the underlying investment being hedged, the Company may enter into new forwards and options near maturity of the existing derivative in order to continue hedging the underlying investment. In forward transactions, Aflac Japan agrees with another party to buy a fixed amount of yen and sell a corresponding amount of U.S. dollars at a specified future date. Aflac Japan also executes foreign currency option transactions in a collar strategy, where Aflac Japan agrees with another party to simultaneously purchase a fixed amount of U.S. dollar put options and sell U.S. dollar call options. The combination of these two actions results in no net premium being paid (i.e. a costless or zero-cost collar). The foreign currency forwards and options are used in fair value hedging relationships to mitigate the foreign exchange risk associated with U.S. dollar-denominated investments supporting yen-denominated liabilities. Foreign currency forwards and options are also used to hedge the currency risk associated with the net investment in Aflac Japan. In these forward transactions, Aflac agrees with another party to buy a fixed amount of U.S. dollars and sell a corresponding amount of yen at a specified price at a specified future date. In the option transactions, the Company uses a combination of foreign currency options to protect expected future cash flows by simultaneously purchasing yen put options (options that protect against a weakening yen) and selling yen call options (options that limit participation in a strengthening yen). The combination of these two actions create a zero-cost collar. The Company enters into foreign currency swaps pursuant to which it exchanges an initial principal amount in one currency for an initial principal amount of another currency, with an agreement to re-exchange the currencies at a future date at an agreed upon exchange rate. There may also be periodic exchanges of payments at specified intervals based on the agreed upon rates and notional amounts. Foreign currency swaps are used primarily in the consolidated VIEs in the Company's Aflac Japan portfolio to convert foreign-denominated cash flows to yen, the functional currency of Aflac Japan, in order to minimize cash flow fluctuations. The Company also uses foreign currency swaps to economically convert certain of its U.S. dollar-denominated senior note and subordinated debenture principal and interest obligations into yen-denominated obligations. The only CDS that the Company currently holds relates to components of an investment in a VIE and is used to assume credit risk related to an individual security. This CDS contract entitles the consolidated VIE to receive periodic fees in exchange for an obligation to compensate the derivative counterparties should the referenced security issuer experience a credit event, as defined in the contract. Derivative Balance Sheet Classification The tables below summarize the balance sheet classification of the Company's derivative fair value amounts, as well as the gross asset and liability fair value amounts. The fair value amounts presented do not include income accruals. The notional amount of derivative contracts represents the basis upon which pay or receive amounts are calculated and are not reflective of exposure or credit risk. June 30, 2018 December 31, 2017 (In millions) Asset Liability Asset Liability Hedge Designation/ Derivative Notional Fair Value Fair Value Notional Fair Value Fair Value Cash flow hedges: Foreign currency swaps $ 75 $ 1 $ (4 ) $ 75 $ 0 $ (8 ) Total cash flow hedges 75 1 (4 ) 75 0 (8 ) Fair value hedges: Foreign currency forwards 3,310 17 (3 ) 7,640 2 (221 ) Foreign currency options 9,225 0 (5 ) 7,670 0 (2 ) Total fair value hedges 12,535 17 (8 ) 15,310 2 (223 ) Net investment hedge: Foreign currency forwards 0 0 0 5 0 0 Foreign currency options 0 0 0 434 12 (1 ) Total net investment hedge 0 0 0 439 12 (1 ) Non-qualifying strategies: Foreign currency swaps 5,390 320 (223 ) 5,386 296 (189 ) Foreign currency forwards 10,410 119 (132 ) 3,683 20 (53 ) Foreign currency options 303 0 0 770 0 0 Credit default swaps 90 0 0 88 1 0 Total non-qualifying strategies 16,193 439 (355 ) 9,927 317 (242 ) Total derivatives $ 28,803 $ 457 $ (367 ) $ 25,751 $ 331 $ (474 ) Balance Sheet Location Other assets $ 17,559 $ 457 $ 0 $ 10,948 $ 331 $ 0 Other liabilities 11,244 0 (367 ) 14,803 0 (474 ) Total derivatives $ 28,803 $ 457 $ (367 ) $ 25,751 $ 331 $ (474 ) Cash Flow Hedges Certain of the Company's consolidated VIEs have foreign currency swaps that qualify for hedge accounting treatment. For those that have qualified, the Company has designated the derivative as a hedge of the variability in cash flows of a forecasted transaction or of amounts to be received or paid related to a recognized asset (“cash flow” hedge). The maximum length of time for which these cash flows are hedged is eight years. The remaining derivatives in the Company's consolidated VIEs that have not qualified for hedge accounting are included in “non-qualifying strategies.” Fair Value Hedges The Company designates and accounts for certain foreign currency forwards and options as fair value hedges when they meet the requirements for hedge accounting. These foreign currency forwards and options hedge the foreign currency exposure of certain U.S. dollar-denominated investments held in Aflac Japan. The Company recognizes gains and losses on these derivatives and the related hedged items in current earnings within other gains (losses). The change in the fair value of the foreign currency forwards related to the changes in the difference between the spot rate and the forward price is excluded from the assessment of hedge effectiveness. The change in fair value of the foreign currency option related to the time value of the option is excluded from the assessment of hedge effectiveness. The following table presents the gains and losses on derivatives and the related hedged items in fair value hedges. Fair Value Hedging Relationships (In millions) Hedging Derivatives Hedged Items Hedging Derivatives Hedged Items Total Gains (Losses) Gains (Losses) Gains (Losses) Ineffectiveness Three Months Ended June 30, 2018: Foreign currency Fixed maturity securities $ (215 ) $ (30 ) $ (185 ) $ 186 $ 1 Foreign currency Fixed maturity securities (2 ) (2 ) 0 0 0 Six Months Ended June 30, 2018: Foreign currency forwards Fixed maturity securities $ 199 $ (69 ) $ 268 $ (278 ) $ (10 ) Foreign currency options Fixed maturity securities (3 ) (3 ) 0 0 0 Three Months Ended June 30, 2017: Foreign currency Fixed maturity and equity securities $ (34 ) $ (50 ) $ 16 $ (15 ) $ 1 Foreign currency options Fixed maturity securities (7 ) (7 ) 0 0 0 Six Months Ended June 30, 2017: Foreign currency forwards Fixed maturity and equity securities $ 307 $ (98 ) $ 405 $ (387 ) $ 18 Foreign currency options Fixed maturity securities 17 6 11 (10 ) 1 Net Investment Hedge The Company's investment in Aflac Japan is affected by changes in the yen/dollar exchange rate. To mitigate this exposure, the Parent Company's yen-denominated liabilities (see Note 8) have been designated as non-derivative hedges and, prior to April 1, 2018, foreign currency forwards and options have been designated as derivative hedges of the foreign currency exposure of the Company's net investment in Aflac Japan. The Company's net investment hedge was effective during the three- and six -month periods ended June 30, 2018 and 2017 , respectively. Non-qualifying Strategies For the Company's derivative instruments in consolidated VIEs that do not qualify for hedge accounting treatment, all changes in their fair value are reported in current period earnings within realized investment gains (losses). The amount of gain or loss recognized in earnings for the Company's VIEs is attributable to the derivatives in those investment structures. While the change in value of the swaps is recorded through current period earnings, the change in value of the available-for-sale fixed maturity securities associated with these swaps is recorded through other comprehensive income. As of June 30, 2018 , the Parent Company had cross-currency interest rate swap agreements related to its $550 million senior notes due March 2020, $350 million senior notes due February 2022, $700 million senior notes due June 2023, $750 million senior notes due November 2024 and $450 million senior notes due March 2025. Changes in the values of these swaps are recorded through current period earnings. For additional information regarding these swaps, see Note 8 in this report and Note 9 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report. The Company uses foreign exchange forwards and options to mitigate the currency risk of some of its U.S. dollar-denominated loan receivables held within the Aflac Japan segment. The Company has not elected to apply hedge accounting for these loan receivables due to the change in fair value of the foreign exchange forwards and the foreign currency remeasurement of the loan receivables being recorded through current period earnings, and generally offsetting each other within realized investment gains (losses). In order to economically mitigate currency risk of future yen dividends from Aflac Japan while lowering consolidated hedge costs associated with Aflac Japan's U.S. dollar investment hedging, starting in the first quarter of 2018, the Parent Company began entering into offsetting hedge positions using foreign exchange forwards. This activity is reported in the Corporate and other segment. Impact of Derivatives and Hedging Instruments The following table summarizes the impact to realized investment gains (losses) and other comprehensive income (loss) from all derivatives and hedging instruments. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (In millions) Realized Investment Other (1) Realized Investment Other (1) Realized Investment Other (1) Realized Investment Other (1) Qualifying hedges: Cash flow hedges: Foreign currency swaps $ 0 $ (2 ) $ 0 $ (2 ) $ 1 $ 4 $ 0 $ 1 Total cash flow hedges 0 (2 ) 0 (2 ) 1 4 0 1 Fair value hedges: Foreign currency forwards (2) (29 ) (49 ) (79 ) (80 ) Foreign currency options (2) (2 ) (7 ) (3 ) 7 Total fair value hedges (31 ) (56 ) (82 ) (73 ) Net investment hedge: Non- derivative hedging instruments 0 55 0 (1 ) 0 (29 ) 0 (18 ) Foreign currency forwards 0 0 0 (19 ) 0 0 0 (28 ) Foreign currency options 0 0 0 31 0 (8 ) 0 8 Total net investment hedge 0 55 0 11 0 (37 ) 0 (38 ) Non-qualifying strategies: Foreign currency swaps 14 34 28 26 Foreign currency forwards (154 ) (29 ) 25 (56 ) Foreign currency options (1 ) 0 0 0 Total non- qualifying strategies (141 ) 5 53 (30 ) Total $ (172 ) $ 53 $ (51 ) $ 9 $ (28 ) $ (33 ) $ (103 ) $ (37 ) (1) Cash flow hedge items are recorded as unrealized gains (losses) on derivatives and net investment hedge items are recorded in the unrealized foreign currency translation gains (losses) line in the consolidated statement of comprehensive income (loss). (2) Impact shown net of effect of hedged items (see Fair Value Hedges section of this Note 4 for further detail) The Company reclassified an immaterial amount related to its cash flow hedges from accumulated other comprehensive income (loss) into earnings for the three- and six -month periods ended June 30, 2018 and 2017. There was no gain or loss reclassified from accumulated other comprehensive income (loss) into earnings related to the net investment hedge for the three- and six -month periods ended June 30, 2018 and 2017 . As of June 30, 2018 , deferred gains and losses on derivative instruments recorded in accumulated other comprehensive income that are expected to be reclassified to earnings during the next twelve months were immaterial. Credit Risk Assumed through Derivatives For the foreign currency and credit default swaps associated with the Company's VIE investments for which it is the primary beneficiary, the Company bears the risk of loss due to counterparty default even though it is not a direct counterparty to those contracts. The Company is a direct counterparty to the foreign currency swaps that it has entered into in connection with certain of its senior notes and subordinated debentures; foreign currency forwards; foreign currency options; and interest rate swaptions, and therefore the Company is exposed to credit risk in the event of nonperformance by the counterparties in those contracts. The risk of counterparty default for the Company's foreign currency swaps, certain foreign currency forwards, foreign currency options and interest rate swaptions is mitigated by collateral posting requirements that counterparties to those transactions must meet. As of June 30, 2018 , there were 15 counterparties to the Company's derivative agreements, with four comprising 60% of the aggregate notional amount. The counterparties to these derivatives are financial institutions with the following credit ratings: June 30, 2018 December 31, 2017 (In millions) Notional Amount Asset Derivatives Liability Derivatives Notional Amount Asset Derivatives Liability Derivatives Counterparties' credit rating: AA $ 5,122 $ 78 $ (12 ) $ 4,708 $ 52 $ (37 ) A 23,237 375 (302 ) 20,604 271 (370 ) BBB 444 4 (53 ) 439 8 (67 ) Total $ 28,803 $ 457 $ (367 ) $ 25,751 $ 331 $ (474 ) The Company engages in derivative transactions directly with unaffiliated third parties under International Swaps and Derivatives Association, Inc. (ISDA) agreements and other documentation. Most of the ISDA agreements also include Credit Support Annexes (CSAs) provisions, which generally provide for two-way collateral postings at the first dollar of exposure. The Company mitigates the risk that counterparties to transactions might be unable to fulfill their contractual obligations by monitoring counterparty credit exposure and collateral value while generally requiring that collateral be posted at the outset of the transaction. In addition, a significant portion of the derivative transactions have provisions that give the counterparty the right to terminate the transaction upon a downgrade of Aflac’s financial strength rating. The actual amount of payments that the Company could be required to make depends on market conditions, the fair value of outstanding affected transactions, and other factors prevailing at and after the time of the downgrade. Collateral posted by the Company to third parties for derivative transactions can generally be repledged or resold by the counterparties. The aggregate fair value of all derivative instruments with credit-risk-related contingent features that were in a net liability position by counterparty was approximately $160 million and $264 million as of June 30, 2018 , and December 31, 2017 , respectively. If the credit-risk-related contingent features underlying these agreements had been triggered on June 30, 2018 , the Company estimates that it would be required to post a maximum of $36 million of additional collateral to these derivative counterparties. The Company is generally allowed to sell or repledge collateral obtained from its derivative counterparties, although it does not typically exercise such rights. (See the Offsetting tables below for collateral posted or received as of the reported balance sheet dates.) Offsetting of Financial Instruments and Derivatives Most of the Company's derivative instruments are subject to enforceable master netting arrangements that provide for the net settlement of all derivative contracts between the Parent Company or Aflac and its respective counterparty in the event of default or upon the occurrence of certain termination events. Collateral support agreements with the master netting arrangements generally provide that the Company will receive or pledge financial collateral at the first dollar of exposure. The Company has securities lending agreements with unaffiliated financial institutions that post collateral to the Company in return for the use of its fixed maturity and public equity securities (see Note 3). When the Company has entered into securities lending agreements with the same counterparty, the agreements generally provide for net settlement in the event of default by the counterparty. This right of set-off allows the Company to keep and apply collateral received if the counterparty failed to return the securities borrowed from the Company as contractually agreed. The tables below summarize the Company's derivatives and securities lending transactions, and as reflected in the tables, in accordance with U.S. GAAP, the Company's policy is to not offset these financial instruments in the Consolidated Balance Sheets. Offsetting of Financial Assets and Derivative Asset June 30, 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement $ 255 $ 0 $ 255 $ (138 ) $ (32 ) $ (82 ) $ 3 Derivative assets not subject to a master netting agreement or offsetting arrangement 202 202 202 Total derivative assets 457 0 457 (138 ) (32 ) (82 ) 205 Securities lending and similar arrangements 3,638 0 3,638 0 0 (3,638 ) 0 Total $ 4,095 $ 0 $ 4,095 $ (138 ) $ (32 ) $ (3,720 ) $ 205 December 31, 2017 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement $ 180 $ 0 $ 180 $ (82 ) $ 0 $ (98 ) $ 0 Derivative assets not subject to a master netting agreement or offsetting arrangement 151 151 151 Total derivative assets 331 0 331 (82 ) 0 (98 ) 151 Securities lending and similar arrangements 592 0 592 0 0 (592 ) 0 Total $ 923 $ 0 $ 923 $ (82 ) $ 0 $ (690 ) $ 151 Offsetting of Financial Liabilities and Derivative Liabilities June 30, 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement $ (276 ) $ 0 $ (276 ) $ 138 $ 73 $ 51 $ (14 ) Derivative liabilities not subject to a master netting agreement or offsetting arrangement (91 ) (91 ) (91 ) Total derivative liabilities (367 ) 0 (367 ) 138 73 51 (105 ) Securities lending and similar arrangements (3,712 ) 0 (3,712 ) 3,638 0 0 (74 ) Total $ (4,079 ) $ 0 $ (4,079 ) $ 3,776 $ 73 $ 51 $ (179 ) December 31, 2017 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement $ (346 ) $ 0 $ (346 ) $ 82 $ 245 $ 10 $ (9 ) Derivative liabilities not subject to a master netting agreement or offsetting arrangement (128 ) (128 ) (128 ) Total derivative liabilities (474 ) 0 (474 ) 82 245 10 (137 ) Securities lending and similar arrangements (606 ) 0 (606 ) 592 0 0 (14 ) Total $ (1,080 ) $ 0 $ (1,080 ) $ 674 $ 245 $ 10 $ (151 ) For additional information on the Company's financial instruments, see the accompanying Notes 1, 3 and 5 and Notes 1, 3 and 5 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS Fair Value Hierarchy U.S. GAAP specifies a hierarchy of valuation techniques based on whether the inputs to those valuation techniques are observable or unobservable. These two types of inputs create three valuation hierarchy levels. Level 1 valuations reflect quoted market prices for identical assets or liabilities in active markets. Level 2 valuations reflect quoted market prices for similar assets or liabilities in an active market, quoted market prices for identical or similar assets or liabilities in non-active markets or model-derived valuations in which all significant valuation inputs are observable in active markets. Level 3 valuations reflect valuations in which one or more of the significant inputs are not observable in an active market. The following tables present the fair value hierarchy levels of the Company's assets and liabilities that are measured and carried at fair value on a recurring basis. June 30, 2018 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: (1) Government and agencies $ 33,591 $ 1,525 $ 0 $ 35,116 Municipalities 0 1,928 0 1,928 Mortgage- and asset-backed securities 0 169 178 347 Public utilities 0 7,258 106 7,364 Sovereign and supranational 0 1,743 0 1,743 Banks/financial institutions 0 9,159 23 9,182 Other corporate 0 30,005 196 30,201 Total fixed maturity securities 33,591 51,787 503 85,881 (1) Equity securities (1) 1,011 75 17 1,103 (1) Other investments 1 0 0 1 Cash and cash equivalents 3,847 0 0 3,847 Other assets: Foreign currency swaps 0 119 202 321 Foreign currency forwards 0 136 0 136 Total other assets 0 255 202 457 Total assets $ 38,450 $ 52,117 $ 722 $ 91,289 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 135 $ 92 $ 227 Foreign currency forwards 0 135 0 135 Foreign currency options 0 5 0 5 Total liabilities $ 0 $ 275 $ 92 $ 367 (1) Includes perpetual securities December 31, 2017 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: (1) Government and agencies $ 30,109 $ 1,121 $ 0 $ 31,230 Municipalities 0 1,370 0 1,370 Mortgage- and asset-backed securities 0 269 175 444 Public utilities 0 7,886 68 7,954 Sovereign and supranational 0 1,909 0 1,909 Banks/financial institutions 0 8,908 25 8,933 Other corporate 0 32,327 146 32,473 Total fixed maturity securities 30,109 53,790 414 84,313 (1) Equity securities 1,001 6 16 1,023 Other investments 57 0 0 57 Cash and cash equivalents 3,491 0 0 3,491 Other assets: Foreign currency swaps 0 146 150 296 Foreign currency forwards 0 22 0 22 Foreign currency options 0 12 0 12 Credit default swaps 0 0 1 1 Total other assets 0 180 151 331 Total assets $ 34,658 $ 53,976 $ 581 $ 89,215 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 69 $ 128 $ 197 Foreign currency forwards 0 274 0 274 Foreign currency options 0 3 0 3 Total liabilities $ 0 $ 346 $ 128 $ 474 (1) Includes perpetual securities The following tables present the carrying amount and fair value categorized by fair value hierarchy level for the Company's financial instruments that are not carried at fair value. June 30, 2018 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 21,808 $ 27,209 $ 8 $ 0 $ 27,217 Municipalities 363 0 474 0 474 Mortgage and asset-backed 16 0 0 17 17 Public utilities 3,236 0 3,552 0 3,552 Sovereign and 1,557 0 1,843 0 1,843 Banks/financial institutions 1,532 0 1,700 0 1,700 Other corporate 2,747 0 3,153 0 3,153 Other investments (1) 5,329 0 19 5,297 5,316 Total assets $ 36,588 $ 27,209 $ 10,749 $ 5,314 $ 43,272 Liabilities: Other policyholders’ funds $ 7,140 $ 0 $ 0 $ 7,060 $ 7,060 Notes payable 5,299 0 5,110 270 5,380 Total liabilities $ 12,439 $ 0 $ 5,110 $ 7,330 $ 12,440 (1) Excludes policy loans of $222 and equity method investments of $279 , at carrying value December 31, 2017 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 21,331 $ 26,491 $ 0 $ 0 $ 26,491 Municipalities 357 0 462 0 462 Mortgage and asset-backed 26 0 8 19 27 Public utilities 3,300 0 3,698 0 3,698 Sovereign and 1,523 0 1,835 0 1,835 Banks/financial institutions 2,206 0 2,387 0 2,387 Other corporate 2,687 0 3,172 0 3,172 Other investments (1) 3,017 0 15 2,987 3,002 Total assets $ 34,447 $ 26,491 $ 11,577 $ 3,006 $ 41,074 Liabilities: Other policyholders’ funds $ 6,939 $ 0 $ 0 $ 6,841 $ 6,841 Notes payable 5,267 0 5,288 265 5,553 Total liabilities $ 12,206 $ 0 $ 5,288 $ 7,106 $ 12,394 (1) Excludes policy loans of $210 and equity method investments of $118 , at carrying value Fair Value of Financial Instruments Fixed maturity and equity securities The Company determines the fair values of fixed maturity securities and public and privately-issued equity securities using the following approaches or techniques: price quotes and valuations from third party pricing vendors (including quoted market prices readily available from public exchange markets) and non-binding price quotes the Company obtains from outside brokers. A third party pricing vendor has developed valuation models to determine fair values of privately issued securities to reflect the impact of the persistent economic environment and the changing regulatory framework. These models are discounted cash flow (DCF) valuation models, but also use information from related markets, specifically the CDS market to estimate expected cash flows. These models take into consideration any unique characteristics of the securities and make various adjustments to arrive at an appropriate issuer-specific loss adjusted credit curve. This credit curve is then used with the relevant recovery rates to estimate expected cash flows and modeling of additional features, including illiquidity adjustments, if necessary, to price the security by discounting those loss adjusted cash flows. In cases where a credit curve cannot be developed from the specific security features, the valuation methodology takes into consideration other market observable inputs, including: 1) the most appropriate comparable security(ies) of the issuer; 2) issuer-specific CDS spreads; 3) bonds or CDS spreads of comparable issuers with similar characteristics such as rating, geography, or sector; or 4) bond indices that are comparative in rating, industry, maturity and region. The pricing data and market quotes the Company obtains from outside sources, including third party pricing services, are reviewed internally for reasonableness. If a fair value appears unreasonable, the Company will re-examine the inputs and assess the reasonableness of the pricing data with the vendor. Additionally, the Company may compare the inputs to relevant market indices and other performance measurements. Based on management's analysis, the valuation is confirmed or may be revised if there is evidence of a more appropriate estimate of fair value based on available market data. The Company has performed verification of the inputs and calculations in any valuation models to confirm that the valuations represent reasonable estimates of fair value. The fixed maturity securities classified as Level 3 consist of securities with limited or no observable valuation inputs. For Level 3 securities, the Company estimates the fair value of these securities by obtaining non-binding broker quotes from a limited number of brokers. These brokers base their quotes on a combination of their knowledge of the current pricing environment and market conditions. The Company considers these inputs to be unobservable. The Company also considers a variety of significant valuation inputs in the valuation process, including forward exchange rates, yen swap rates, dollar swap rates, interest rate volatilities, credit spread data on specific issuers, assumed default and default recovery rates, and certain probability assumptions. In obtaining these valuation inputs, the Company has determined that certain pricing assumptions and data used by its pricing sources are difficult to validate or corroborate by the market and/or appear to be internally developed rather than observed in or corroborated by the market. The use of these unobservable valuation inputs causes more subjectivity in the valuation process for these securities. For the periods presented, the Company has not adjusted the quotes or prices it obtains from the pricing services and brokers it uses. The following tables present the pricing sources for the fair values of the Company's fixed maturity and equity securities. June 30, 2018 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: (1) Government and agencies: Third party pricing vendor $ 33,591 $ 1,525 $ 0 $ 35,116 Total government and agencies 33,591 1,525 0 35,116 Municipalities: Third party pricing vendor 0 1,928 0 1,928 Total municipalities 0 1,928 0 1,928 Mortgage- and asset-backed securities: Third party pricing vendor 0 169 0 169 Broker/other 0 0 178 178 Total mortgage- and asset-backed securities 0 169 178 347 Public utilities: Third party pricing vendor 0 7,258 0 7,258 Broker/other 0 0 106 106 Total public utilities 0 7,258 106 7,364 Sovereign and supranational: Third party pricing vendor 0 1,743 0 1,743 Total sovereign and supranational 0 1,743 0 1,743 Banks/financial institutions: Third party pricing vendor 0 8,959 0 8,959 Broker/other 0 200 23 223 Total banks/financial institutions 0 9,159 23 9,182 Other corporate: Third party pricing vendor 0 30,005 0 30,005 Broker/other 0 0 196 196 Total other corporate 0 30,005 196 30,201 Total securities available for sale $ 33,591 $ 51,787 $ 503 $ 85,881 (1) Equity securities, carried at fair value: (1) Third party pricing vendor $ 961 $ 75 $ 0 $ 1,036 Broker/other 50 0 17 67 Total equity securities $ 1,011 $ 75 $ 17 $ 1,103 (1) (1) Includes perpetual securities June 30, 2018 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 27,209 $ 8 $ 0 $ 27,217 Total government and agencies 27,209 8 0 27,217 Municipalities: Third party pricing vendor 0 474 0 474 Total municipalities 0 474 0 474 Mortgage- and asset-backed securities: Broker/other 0 0 17 17 Total mortgage- and asset-backed securities 0 0 17 17 Public utilities: Third party pricing vendor 0 3,552 0 3,552 Total public utilities 0 3,552 0 3,552 Sovereign and supranational: Third party pricing vendor 0 1,843 0 1,843 Total sovereign and supranational 0 1,843 0 1,843 Banks/financial institutions: Third party pricing vendor 0 1,700 0 1,700 Total banks/financial institutions 0 1,700 0 1,700 Other corporate: Third party pricing vendor 0 3,153 0 3,153 Total other corporate 0 3,153 0 3,153 Total securities held to maturity $ 27,209 $ 10,730 $ 17 $ 37,956 December 31, 2017 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: (1) Government and agencies: Third party pricing vendor $ 30,109 $ 1,121 $ 0 $ 31,230 Total government and agencies 30,109 1,121 0 31,230 Municipalities: Third party pricing vendor 0 1,370 0 1,370 Total municipalities 0 1,370 0 1,370 Mortgage- and asset-backed securities: Third party pricing vendor 0 269 0 269 Broker/other 0 0 175 175 Total mortgage- and asset-backed securities 0 269 175 444 Public utilities: Third party pricing vendor 0 7,886 0 7,886 Broker/other 0 0 68 68 Total public utilities 0 7,886 68 7,954 Sovereign and supranational: Third party pricing vendor 0 1,807 0 1,807 Broker/other 0 102 0 102 Total sovereign and supranational 0 1,909 0 1,909 Banks/financial institutions: Third party pricing vendor 0 8,908 0 8,908 Broker/other 0 0 25 25 Total banks/financial institutions 0 8,908 25 8,933 Other corporate: Third party pricing vendor 0 32,327 0 32,327 Broker/other 0 0 146 146 Total other corporate 0 32,327 146 32,473 Total fixed maturity securities 30,109 53,790 414 84,313 Total securities available for sale $ 30,109 $ 53,790 $ 414 $ 84,313 (1) Equity securities, carried at fair value: Third party pricing vendor $ 1,001 $ 6 $ 0 $ 1,007 Broker/other 0 0 16 16 Total equity securities $ 1,001 $ 6 $ 16 $ 1,023 (1) Includes perpetual securities December 31, 2017 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 26,491 $ 0 $ 0 $ 26,491 Total government and agencies 26,491 0 0 26,491 Municipalities: Third party pricing vendor 0 462 0 462 Total municipalities 0 462 0 462 Mortgage- and asset-backed securities: Third party pricing vendor 0 8 0 8 Broker/other 0 0 19 19 Total mortgage- and asset-backed securities 0 8 19 27 Public utilities: Third party pricing vendor 0 3,698 0 3,698 Total public utilities 0 3,698 0 3,698 Sovereign and supranational: Third party pricing vendor 0 1,835 0 1,835 Total sovereign and supranational 0 1,835 0 1,835 Banks/financial institutions: Third party pricing vendor 0 2,387 0 2,387 Total banks/financial institutions 0 2,387 0 2,387 Other corporate: Third party pricing vendor 0 3,172 0 3,172 Total other corporate 0 3,172 0 3,172 Total securities held to maturity $ 26,491 $ 11,562 $ 19 $ 38,072 The following is a discussion of the determination of fair value of the Company's remaining financial instruments. Derivatives The Company uses derivative instruments to manage the risk associated with certain assets. However, the derivative instrument may not be classified in the same fair value hierarchy level as the associated asset. Inputs used to value derivatives include, but are not limited to, interest rates, credit spreads, foreign currency forward and spot rates, and interest volatility. The fair values of the foreign currency forwards and options associated with certain investments; the foreign currency forwards and options used to hedge foreign exchange risk from the Company's net investment in Aflac Japan and economically hedge certain portions of forecasted cash flows denominated in yen; and the foreign currency swaps associated with certain senior notes and subordinated debentures are based on the amounts the Company would expect to receive or pay. The determination of the fair value of these derivatives is based on observable market inputs, therefore they are classified as Level 2. For derivatives associated with VIEs where the Company is the primary beneficiary, the Company is not the direct counterparty to the swap contracts. As a result, the fair value measurements incorporate the credit risk of the collateral associated with the VIE. The Company receives valuations from a third party pricing vendor for these derivatives. Based on an analysis of these derivatives and a review of the methodology employed by the pricing vendor, the Company determined that due to the long duration of these swaps and the need to extrapolate from short-term observable data to derive and measure long-term inputs, certain inputs, assumptions and judgments are required to value future cash flows that cannot be corroborated by current inputs or current observable market data. As a result, the derivatives associated with the Company's consolidated VIEs are classified as Level 3 of the fair value hierarchy. Other investments Other investments where fair value is disclosed above include short-term investments and loan receivables. Loan receivables include transitional real estate loans, commercial mortgage loans and middle market loans. The Company's loan receivables do not have readily determinable market prices and generally lack market liquidity. Fair values for loan receivables are determined based on the present value of expected future cash flows discounted at the applicable U.S. Treasury or London Interbank Offered Rate (LIBOR) yield plus an appropriate spread that considers other risk factors, such as credit and liquidity risk. These spreads are provided by the applicable asset managers based on their knowledge of the current loan pricing environment and market conditions. The spreads are a significant component of the pricing inputs and are generally considered unobservable. Therefore, these investments have been assigned a Level 3 within the fair value hierarchy. Other policyholders' funds The largest component of the other policyholders' funds liability is the Company's annuity line of business in Aflac Japan. The Company's annuities have fixed benefits and premiums. For this product, the Company estimates the fair value to be equal to the cash surrender value. This is analogous to the value paid to policyholders on the valuation date if they were to surrender their policy. The Company periodically checks the cash value against discounted cash flow projections for reasonableness. The Company considers its inputs for this valuation to be unobservable and have accordingly classified this valuation as Level 3. Notes payable The fair values of the Company's publicly issued notes payable are determined by utilizing available sources of observable inputs from third party pricing vendors and are classified as Level 2. The fair values of the Company's yen-denominated loans approximate their carrying values and are classified as Level 3. Transfers between Hierarchy Levels and Level 3 Rollforward During the three- and six -month periods ended June 30, 2018 and 2017 , respectively, there were no transfers between Level 1 and 2 for assets and liabilities that are measured and carried at fair value on a recurring basis. The following tables present the changes in fair value of the Company's investments and derivatives carried at fair value classified as Level 3. Three Months Ended Fixed Maturities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 186 $ 83 $ 24 $ 143 $ 16 $ 154 $ 1 $ 607 Realized investment gains (losses) included in earnings 0 0 0 0 0 (42 ) (1 ) (43 ) Unrealized gains (losses) included in other comprehensive income (loss) (8 ) (1 ) (1 ) (1 ) 0 (2 ) 0 (13 ) Purchases, issuances, sales and settlements: Purchases 0 24 0 56 1 0 0 81 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements 0 0 0 (2 ) 0 0 0 (2 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 178 $ 106 $ 23 $ 196 $ 17 $ 110 $ 0 $ 630 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ (42 ) $ (1 ) $ (43 ) (1) Derivative assets and liabilities are presented net Three Months Ended Fixed Maturities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 195 $ 16 $ 24 $ 35 $ 4 $ 19 $ 2 $ 295 Realized investment gains (losses) included in 0 0 0 0 0 (10 ) 0 (10 ) Unrealized gains (losses) included in other 0 0 1 2 0 (2 ) 0 1 Purchases, issuances, sales and settlements: Purchases 0 37 0 40 10 0 0 87 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements (7 ) 0 0 0 0 0 0 (7 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 188 $ 53 $ 25 $ 77 $ 14 $ 7 $ 2 $ 366 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ (10 ) $ 0 $ (10 ) (1) Derivative assets and liabilities are presented net Six Months Ended Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 175 $ 68 $ 25 $ 146 $ 16 $ 22 $ 1 $ 453 Realized investment gains (losses) included 0 0 0 0 0 84 (1 ) 83 Unrealized gains (losses) included in other 3 (2 ) (2 ) (3 ) 0 4 0 0 Purchases, issuances, sales and settlements: Purchases 0 40 0 56 1 0 0 97 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements 0 0 0 (3 ) 0 0 0 (3 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 178 $ 106 $ 23 $ 196 $ 17 $ 110 $ 0 $ 630 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ 84 $ (1 ) $ 83 (1) Derivative assets and liabilities are presented net Six Months Ended Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 198 $ 16 $ 25 $ 0 $ 3 $ (21 ) $ 2 $ 223 Realized investment gains (losses) included in earnings 0 0 0 0 0 28 0 28 Unrealized gains (losses) included in other comprehensive income (loss) 6 0 0 2 0 0 0 8 Purchases, issuances, sales and settlements: Purchases 0 37 0 75 12 0 0 124 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 (1 ) 0 0 (1 ) Settlements (16 ) 0 0 0 0 0 0 (16 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 188 $ 53 $ 25 $ 77 $ 14 $ 7 $ 2 $ 366 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ 28 $ 0 $ 28 (1) Derivative assets and liabilities are presented net Fair Value Sensitivity Level 3 Significant Unobservable Input Sensitivity The following tables summarize the significant unobservable inputs used in the valuation of the Company's Level 3 investments and derivatives carried at fair value. Included in the tables are the inputs or range of possible inputs that have an effect on the overall valuation of the financial instruments. June 30, 2018 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 178 Consensus pricing Offered quotes N/A (c) Public utilities 106 Discounted cash flow Credit spreads N/A (c) Banks/financial institutions 23 Consensus pricing Offered quotes N/A (c) Other corporate 196 Discounted cash flow Credit spreads N/A (c) Equity securities 17 Net asset value Offered quotes N/A (c) Other assets: Foreign currency swaps 145 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) CDS spreads 15 - 105 bps 57 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) Total assets $ 722 Liabilities: Other liabilities: Foreign currency swaps $ 88 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) CDS spreads 34 - 188 bps 4 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) Total liabilities $ 92 (a) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (b) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps (c) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. December 31, 2017 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 175 Consensus pricing Offered quotes N/A (c) Public utilities 68 Discounted cash flow Credit spreads N/A (c) Banks/financial institutions 25 Consensus pricing Offered quotes N/A (c) Other corporate 146 Discounted cash flow Credit spreads N/A (c) Equity securities 16 Net asset value Offered quotes N/A (c) Other assets: Foreign currency swaps 80 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) CDS spreads 9 - 90 bps 70 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) Credit default swaps 1 Discounted cash flow Base correlation 46.33% - 49.65% (d) CDS spreads 25 bps Recovery rate 37.24% Total assets $ 581 Liabilities: Other liabilities: Foreign currency swaps $ 120 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) CDS spreads 13 - 157 bps 8 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) Total liabilities $ 128 (a) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (b) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps (c) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. (d) Range of base correlation for the Company's bespoke tranche for attachment and detachment points corresponding to market indices The following is a discussion of the significant unobservable inputs or valuation techniques used in determining the fair value of securities and derivatives classified as Level 3. Net Asset Value The Company holds certain unlisted equity securities whose fair value is derived based on the financial statements published by the investee. These securities do not trade on an active market and the valuations derived are dependent on the availability of timely financial reporting of the investee. Net asset value is an unobservable input in the determination of fair value of equity securities. Offered Quotes In circumstances where the Company's valuation model price is overridden because it implies a value that is not consistent with current market conditions, the Company will solicit bids from a limited number of brokers. The Company also receives unadjusted prices from brokers for its mortgage and asset-backed securities. These quotes are non-binding but are reflective of valuation best estimates at that particular point in time. Offered quotes are an unobservable input in the determination of fair value of mortgage- and asset-backed securities, certain banks/financial institutions, certain other corporate, and equity securities investments. Interest Rates, CDS Spreads, Foreign Exchange Rates The significant drivers of the valuation of the interest and foreign exchange swaps are interest rates, foreign exchange rates and CDS spreads. Some of the Company's swaps have long maturities that increase the sensitivity of the swaps to interest rate fluctuations. For the Company's foreign exchange or cross currency swaps that are in a net asset position, an increase in yen interest rates (all other factors held constant) will decrease the present value of the yen final settlement receivable (receive leg), thus decreasing the value of the swap as long as the derivative remains in a net asset position. Foreign exchange swaps also have a lump-sum final settlement of foreign exchange principal amounts at the termination of the swap. Assuming all other factors are held constant, an increase in yen interest rates will decrease the receive leg and decrease the net value of the swap. Likewise, holding all other factors constant, an increase in U.S. dollar interest rates will increase the swap's net value due to the decrease in the present value of the dollar final settlement payable (pay leg). A similar sensitivity pattern is observed for the foreign exchange rates. When the spot U.S. dollar/Japanese yen (USD/JPY) foreign exchange rate decreases and the swap is receiving a final exchange payment in JPY, the swap value will increase due to the appreciation of the JPY. Most of the Company's swaps are designed to receive payments in JPY at the termination and will thus be impacted by the USD/JPY foreign exchange rate in this way. In cases where there is no final foreign exchange receivable in JPY and the Company is paying JPY as interest payments and receiving USD, a decrease in the foreign exchange rate will lead to a decrease in the swap value. The extinguisher feature in most of the Company's VIE swaps results in a cessation of cash flows and no further payments between the parties to the swap in the event of a default on the referenced or underlying collateral. To price this feature, the Company applies the survival probability of the referenced entity to the projected cash flows. The survival probability uses the CDS spreads and recovery rates to adjust the present value of the cash flows. For extinguisher swaps with positive values, an increase in CDS spreads decreases the likelihood of receiving the final exchange payments and reduces the value of the swap. For additional information on the Company's investments and financial instruments, see the accompanying Notes 1, 3 and 4 and Notes 1, 3 and 4 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report.

POLICY LIABILITIES

POLICY LIABILITIES	6 Months Ended
	Jun. 30, 2018
Insurance Loss Reserves [Abstract]
POLICY LIABILITIES	POLICY LIABILITIES Changes in the liability for unpaid policy claims were as follows: Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Unpaid supplemental health claims, beginning of period $ 4,041 $ 3,854 $ 3,881 $ 3,707 Less reinsurance recoverables 31 30 28 27 Net balance, beginning of period 4,010 3,824 3,853 3,680 Add claims incurred during the period related to: Current year 1,779 1,772 3,621 3,520 Prior years (133 ) (138 ) (325 ) (260 ) Total incurred 1,646 1,634 3,296 3,260 Less claims paid during the period on claims incurred during: Current year 1,226 1,220 1,746 1,721 Prior years 426 400 1,540 1,461 Total paid 1,652 1,620 3,286 3,182 Effect of foreign exchange rate changes on unpaid claims (91 ) 4 50 84 Net balance, end of period 3,913 3,842 3,913 3,842 Add reinsurance recoverables 29 30 29 30 Unpaid supplemental health claims, end of period 3,942 3,872 3,942 3,872 Unpaid life claims, end of period 582 409 582 409 Total liability for unpaid policy claims $ 4,524 $ 4,281 $ 4,524 $ 4,281 The incurred claims development related to prior years reflects favorable claims experience compared to previous estimates. The favorable claims development of $325 million for the six -month period ended June 30, 2018 comprises approximately $210 million from Japan, which represents approximately 65% of the total. Excluding the impact of foreign exchange of a loss of approximately $10 million from December 31, 2017 to June 30, 2018 , the favorable claims development in Japan would have been approximately $200 million , representing approximately 62% of the total. The Company has experienced continued favorable claim trends in 2018 for its core health products in Japan. The Company's experience in Japan related to the average length of stay in the hospital for cancer treatment has shown continued decline in the current period. In addition, cancer treatment patterns in Japan are continuing to be influenced by significant advances in early-detection techniques and by the increased use of pathological diagnosis rather than clinical exams. Additionally, follow-up radiation and chemotherapy treatments are occurring more often on an outpatient basis. Such changes in treatment not only increase the quality of life and initial outcomes for the patients, but also decrease the average length of each hospital stay, resulting in favorable claims development. The remainder of the favorable claims development related to prior years for the six -month period ended June 30, 2018 , reflects Aflac U.S. favorable claims experience compared to previous estimates, primarily in the cancer and accident lines of business.

REINSURANCE

REINSURANCE	6 Months Ended
	Jun. 30, 2018
Reinsurance Disclosures [Abstract]
REINSURANCE	REINSURANCE The Company periodically enters into fixed quota-share coinsurance agreements with other companies in the normal course of business. For each of its reinsurance agreements, the Company determines whether the agreement provides indemnification against loss or liability relating to insurance risk in accordance with applicable accounting standards. Reinsurance premiums and benefits paid or provided are accounted for on bases consistent with those used in accounting for the original policies issued and the terms of the reinsurance contracts. Premiums and benefits are reported net of insurance ceded. The Company has recorded a deferred profit liability related to reinsurance transactions. The remaining deferred profit liability of $1.0 billion , as of June 30, 2018 , is included in future policy benefits in the consolidated balance sheet and is being amortized into income over the expected lives of the policies. The Company has also recorded a reinsurance recoverable for reinsurance transactions, which is included in other assets in the consolidated balance sheet and had a remaining balance of $935 million and $908 million as of June 30, 2018 , and December 31, 2017 , respectively. The increase in the reinsurance recoverable balance was driven by two aggregating factors: yen strengthening and the growth in reserves related to the business that has been reinsured as the policies age. The spot yen/dollar exchange rate strengthened by approximately 2.2% and ceded reserves increased approximately .7% from December 31, 2017 , to June 30, 2018 . The following table reconciles direct premium income and direct benefits and claims to net amounts after the effect of reinsurance. Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Direct premium income $ 4,793 $ 4,752 $ 9,626 $ 9,476 Ceded to other companies: Ceded Aflac Japan closed blocks (126 ) (130 ) (256 ) (260 ) Other (16 ) (13 ) (30 ) (25 ) Assumed from other companies: Retrocession activities 53 55 107 109 Other 2 1 3 3 Net premium income $ 4,706 $ 4,665 $ 9,450 $ 9,303 Direct benefits and claims $ 3,106 $ 3,117 $ 6,225 $ 6,246 Ceded benefits and change in reserves for future benefits: Ceded Aflac Japan closed blocks (114 ) (119 ) (231 ) (241 ) Eliminations 11 13 23 26 Other (12 ) (11 ) (23 ) (22 ) Assumed from other companies: Retrocession activities 49 52 101 106 Eliminations (11 ) (13 ) (23 ) (26 ) Other 2 0 1 2 Benefits and claims, net $ 3,031 $ 3,039 $ 6,073 $ 6,091 These reinsurance transactions are indemnity reinsurance that do not relieve the Company from its obligations to policyholders. In the event that the reinsurer is unable to meet their obligations, the Company remains liable for the reinsured claims. As a part of its capital contingency plan, the Company entered into a committed reinsurance facility agreement on December 1, 2015 in the amount of approximately 110 billion yen. This reinsurance facility agreement was renewed in 2017 and is effective until December 31, 2018. There are also additional commitment periods of a one-year duration, each of which are automatically extended unless notification is received from the reinsurer within 60 days prior to the expiration. The reinsurer can withdraw from the committed facility if Aflac‘s Standard and Poor's (S&P) rating drops below BBB-. As of June 30, 2018 , the Company has not executed a reinsurance treaty under this committed reinsurance facility.

NOTES PAYABLE

NOTES PAYABLE	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
NOTES PAYABLE	NOTES PAYABLE A summary of notes payable follows: (In millions) June 30, 2018 December 31, 2017 2.40% senior notes due March 2020 $ 549 $ 548 4.00% senior notes due February 2022 348 348 3.625% senior notes due June 2023 697 697 3.625% senior notes due November 2024 746 745 3.25% senior notes due March 2025 446 446 2.875% senior notes due October 2026 297 297 6.90% senior notes due December 2039 220 220 6.45% senior notes due August 2040 254 254 4.00% senior notes due October 2046 394 394 Yen-denominated senior notes and subordinated debentures: .932% senior notes due January 2027 (principal amount 60.0 billion yen) 540 528 2.108% subordinated debentures due October 2047 (principal amount 60.0 billion yen) 538 526 Yen-denominated loans: Variable interest rate loan due September 2021 (.32% in 2018 and 2017, principal amount 5.0 billion yen) 45 44 Variable interest rate loan due September 2023 (.47% in 2018 and 2017, principal amount 25.0 billion yen) 225 220 Capitalized lease obligations payable through 2025 16 22 Total notes payable $ 5,315 $ 5,289 Amounts in the table above are reported net of debt issuance costs and issuance premiums or discounts, if applicable, that are being amortized over the life of the notes. A summary of the Company's lines of credit as of June 30, 2018 follows: Borrower Type Term Expiration Date Capacity Amount Outstanding Interest Rate on Borrowed Amount Maturity Period Commitment Fee Business Purpose Aflac Incorporated uncommitted bilateral 364 days November 30, 2018 $100 million $0 million The rate quoted by the bank and agreed upon at the time of borrowing Up to 3 months None General corporate purposes Aflac Incorporated unsecured revolving 3 years March 31, 2019, or the date commitments are terminated pursuant to an event of default 100.0 billion yen 0.0 billion yen A rate per annum equal to (a) Tokyo interbank market rate (TIBOR) plus, the alternative applicable TIBOR margin during the availability period from the closing date to the commitment termination date or (b) the TIBOR rate offered by the agent to major banks in yen for the applicable period plus, the applicable alternative TIBOR margin during the term out period No later than .30% to .50%, depending on the Parent Company's debt ratings as of the date of determination General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated unsecured revolving 5 years April 4, 2023, or the date commitments are terminated pursuant to an event of default (1) 55.0 billion yen, or the equivalent amount in U.S. dollars 0.0 billion yen A rate per annum equal to, at the Company's option, either, (a) London Interbank Offered Rate (LIBOR) adjusted for certain costs or (b) a base rate determined by reference to the highest of (1) the federal funds rate plus 1/2 of 1%, (2) the rate of interest for such day announced by Mizuho Bank, Ltd. as its prime rate, or (3) the eurocurrency rate for an interest period of one month plus 1.00%, in each case plus an applicable margin No later than April 4, 2023 .085% to .225%, depending on the Parent Company's debt ratings as of the date of determination General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated uncommitted bilateral None specified None specified $50 million $0 million A rate per annum equal to, at the Parent Company's option, either (a) a eurocurrency rate determined by reference to the agent's LIBOR for the interest period relevant to such borrowing or (b) the base rate determined by reference to the greater of (i) the prime rate as determined by the agent, and (ii) the sum of 0.50% and the federal funds rate for such day Up to 3 months None General corporate purposes Aflac (2) uncommitted revolving 364 days November 30, 2018 $250 million $0 million USD three-month LIBOR plus 75 basis points per annum 3 months None General corporate purposes Aflac Incorporated (2) uncommitted revolving 364 days April 2, 2019 37.5 billion yen 0.0 billion yen Three-month TIBOR plus 80 basis points per annum 3 months None General corporate purposes (1) Effective April 4, 2018, the prior expiration date of September 18, 2020 was extended to April 4, 2023. (2) Intercompany credit agreement The Company was in compliance with all of the covenants of its notes payable and lines of credit at June 30, 2018 . No events of default or defaults occurred during the six -month period ended June 30, 2018 . For additional information, see Notes 4 and 9 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report.

INCOME TAXES

INCOME TAXES	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	9. INCOME TAXES For the United States, the Tax Cuts and Jobs Act (Tax Act) was signed into law on December 22, 2017. Effective January 1, 2018, the Tax Act imposes a broad number of changes in tax law, including the permanent reduction of the U.S. federal statutory corporate income tax rate from 35% to 21% . The Company expects to complete its accounting for the effects of the Tax Act over the measurement period of up to one year from the enactment date, as permitted by SEC Staff Accounting Bulletin No. 118 (SAB 118). As of the enactment date, the Company estimated provisional amounts for its deferred taxes, including related valuation allowance, resulting in a reduction of its deferred tax assets (DTAs) by approximately $1.0 billion and its deferred tax liabilities (DTLs) by $2.9 billion , for a net DTL reduction of approximately $1.9 billion . The Company believes that these amounts represent reasonable estimates in accordance with SAB 118. The provisions of ASC 740-10, Income Taxes , require that the effects of changes in tax law on deferred taxes be recognized as a component of the income tax provision in the period the tax rate change was enacted. Therefore, the $1.9 billion provisional amount of net DTL reduction was recorded in the fourth quarter of 2017 as a reduction in the “Income tax expense, Deferred” line item of the Company’s consolidated statement of earnings. As of the second quarter of 2018, the Company has no update to this estimated benefit. The following includes an overview of the existing current and deferred balances for which calculation of income tax effects of the Tax Act has not been completed: Japan deferred tax balances: The Tax Act reduces the U.S. tax rate to 21% , effective January 1, 2018. Prior to the reduction in rate, the Japan deferred tax balances were completely offset by an anticipatory foreign tax credit. As a result of the rate reduction, the Japan deferred tax balance will no longer be offset by an anticipatory foreign tax credit as all of the foreign tax credits will be used to offset the U.S. deferred tax balance of the Aflac Japan branch. The Company has not yet completed its analysis of the components of the Japan tax computation, including a complete validation of the Aflac Japan tax basis. Additional time is needed to collect, analyze, and validate the detailed data underlying the deferred tax amounts in the Aflac Japan branch. As of the fourth quarter of 2017, the Company had recorded a provisional amount of $4.5 billion of net DTL related to this item. Valuation allowances: The Company must assess whether its valuation allowance analyses are impacted by various aspects of the Tax Act with a primary focus on any unused anticipatory foreign tax credits. As the Company has recorded provisional amounts related to the Japan deferred tax balances, any corresponding determination of the need for or change in a valuation allowance is also provisional. As of the fourth quarter of 2017, the Company had recorded a provisional valuation allowance of $.7 billion against its anticipatory foreign tax credit asset. The impact of the Tax Act may differ, possibly materially, from the recorded provisional amounts.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	6 Months Ended
	Jun. 30, 2018
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS’ EQUITY See Note 1 for a discussion of the stock split that occurred in March 2018. All share and per-share amounts have been adjusted to reflect the stock split for any of the periods presented. The following table is a reconciliation of the number of shares of the Company's common stock for the six -month periods ended June 30 . (In thousands of shares) 2018 2017 Common stock - issued: Balance, beginning of period 1,345,762 1,342,498 Exercise of stock options and issuance of restricted shares 1,299 1,576 Balance, end of period 1,347,061 1,344,074 Treasury stock: Balance, beginning of period 564,852 530,877 Purchases of treasury stock: Open market 13,441 22,310 Other 328 346 Dispositions of treasury stock: Shares issued to AFL Stock Plan (400 ) (998 ) Exercise of stock options (327 ) (414 ) Other (105 ) (44 ) Balance, end of period 577,789 552,077 Shares outstanding, end of period 769,272 791,997 Outstanding share-based awards are excluded from the calculation of weighted-average shares used in the computation of basic earnings per share (EPS). The following table presents the approximate number of share-based awards to purchase shares, on a weighted-average basis, that were considered to be anti-dilutive and were excluded from the calculation of diluted earnings per share for the following periods. Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Anti-dilutive share-based awards 48 838 28 740 Share Repurchase Program During the first six months of 2018 , the Company repurchased 13.4 million shares of its common stock in the open market for $601 million as part of its share repurchase program. During the first six months of 2017 , the Company repurchased 22.4 million shares of its common stock in the open market for $800 million as part of its share repurchase program. In August 2017, the Company's board of directors authorized the purchase of an additional 40 million shares of its common stock, which increased to 80 million shares in February 2018 in connection with the Company's stock split scheduled for March 2018. As of June 30, 2018 , a remaining balance of 84.6 million shares of the Company's common stock was available for purchase under share repurchase authorizations by its board of directors. Reclassifications from Accumulated Other Comprehensive Income The tables below are reconciliations of accumulated other comprehensive income by component for the following periods. Changes in Accumulated Other Comprehensive Income Three Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Total Balance, beginning of period $ (1,303 ) $ 5,206 $ (21 ) $ (197 ) $ 3,685 Other comprehensive (1) (463 ) (391 ) (2 ) (1 ) (857 ) Amounts reclassified from 0 21 0 3 24 Net current-period other (463 ) (370 ) (2 ) 2 (833 ) Balance, end of period $ (1,766 ) $ 4,836 $ (23 ) $ (195 ) $ 2,852 All amounts in the table above are net of tax. Three Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,650 ) $ 4,474 $ (22 ) $ (170 ) $ 2,632 Other comprehensive 70 698 (1 ) (2 ) 765 Amounts reclassified from 0 1 0 3 4 Net current-period other 70 699 (1 ) 1 769 Balance, end of period $ (1,580 ) $ 5,173 $ (23 ) $ (169 ) $ 3,401 All amounts in the table above are net of tax. Six Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Total Balance, beginning of period $ (1,750 ) $ 5,964 $ (23 ) $ (163 ) $ 4,028 Cumulative effect of change 0 (148 ) 0 0 (148 ) Cumulative effect of change (325 ) 734 (3 ) (32 ) 374 Other comprehensive (1) 309 (1,733 ) 3 (5 ) (1,426 ) Amounts reclassified from 0 19 0 5 24 Net current-period other 309 (1,714 ) 3 0 (1,402 ) Balance, end of period $ (1,766 ) $ 4,836 $ (23 ) $ (195 ) $ 2,852 All amounts in the table above are net of tax. (1) Amounts have been corrected to exclude the cumulative effects of changes in accounting principles for financial instruments and the tax effects from tax reform as identified in the rollforward of Accumulated Other Comprehensive Income within the Consolidated Statements of Shareholder’s Equity. Six Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,983 ) $ 4,805 $ (24 ) $ (168 ) $ 2,630 Other comprehensive 403 357 1 (6 ) 755 Amounts reclassified from 0 11 0 5 16 Net current-period other 403 368 1 (1 ) 771 Balance, end of period $ (1,580 ) $ 5,173 $ (23 ) $ (169 ) $ 3,401 All amounts in the table above are net of tax. For the six-month period ended June 30, 2018 , see Note 1 for discussion of the amounts reclassified between AOCI and retained earnings upon the adoption of new accounting pronouncements. The tables below summarize the amounts reclassified from each component of accumulated other comprehensive income into net earnings for the following periods. Reclassifications Out of Accumulated Other Comprehensive Income (In millions) Three Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (2 ) Other-than-temporary impairment (26 ) Other gains (losses) (28 ) Total before tax 7 Tax (expense) or benefit (1) $ (21 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (4 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 1 Tax (expense) or benefit (1) $ (3 ) Net of tax Total reclassifications for the period $ (24 ) Net of tax (1) Based on 26% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details). (In millions) Three Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (6 ) Other-than-temporary impairment 5 Other gains (losses) (1 ) Total before tax 0 Tax (expense) or benefit (1) $ (1 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (5 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 2 Tax (expense) or benefit (1) $ (3 ) Net of tax Total reclassifications for the period $ (4 ) Net of tax (1) Based on 35% tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details) (In millions) Six Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (2 ) Other-than-temporary impairment (24 ) Other gains (losses) (26 ) Total before tax 7 Tax (expense) or benefit (1) $ (19 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (8 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 3 Tax (expense) or benefit (1) $ (5 ) Net of tax Total reclassifications for the period $ (24 ) Net of tax (1) Based on 27% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details). (In millions) Six Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (16 ) Other-than-temporary impairment (1 ) Other gains (losses) (17 ) Total before tax 6 Tax (expense) or benefit (1) $ (11 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (8 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 3 Tax (expense) or benefit (1) $ (5 ) Net of tax Total reclassifications for the period $ (16 ) Net of tax (1) Based on 35% tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details)

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
SHARE-BASED COMPENSATION	SHARE-BASED COMPENSATION See Note 1 for a discussion of the stock split that occurred in March 2018. All share and per-share amounts have been adjusted to reflect the stock split for any of the periods presented. As of June 30, 2018 , the Company has outstanding share-based awards under the Aflac Incorporated Long-Term Incentive Plan (the “Plan”). Share-based awards are designed to reward employees for their long-term contributions to the Company and provide incentives for them to remain with the Company. The number and frequency of share-based awards are based on competitive practices, operating results of the Company, government regulations, and other factors. The Plan, as amended on February 14, 2017, allows for a maximum number of shares issuable over its term of 75 million shares including 38 million shares that may be awarded in respect of awards other than options or stock appreciation rights. If any awards granted under the Plan are forfeited or are terminated before being exercised or settled for any reason other than tax forfeiture, then the shares underlying the awards will again be available under the Plan. The Plan allows awards to Company employees for incentive stock options (ISOs), non-qualifying stock options (NQSOs), restricted stock, restricted stock units, and stock appreciation rights. Non-employee directors are eligible for grants of NQSOs, restricted stock, and stock appreciation rights. As of June 30, 2018 , approximately 40.4 million shares were available for future grants under this plan. The ISOs and NQSOs have a term of 10 years, and the share-based awards generally vest upon time-based conditions or time and performance-based conditions. Time-based vesting generally occurs after three years. Performance-based vesting conditions generally include the attainment of goals related to Company financial performance. As of June 30, 2018 , the only performance-based awards issued and outstanding were restricted stock awards. Stock options and stock appreciation rights granted under the amended Plan have an exercise price of at least the fair market value of the underlying stock on the grant date and have an expiration date no later than 10 years from the grant date. Time-based restricted stock awards, restricted stock units and stock options granted after January 1, 2017 generally vest on a ratable basis over three years, and awards granted prior to the amendment vest on a three -year cliff basis. The Compensation Committee of the Board of Directors has the discretion to determine vesting schedules . Share-based awards granted to U.S.-based grantees are settled with authorized but unissued Company stock, while those issued to Japan-based grantees are settled with treasury shares. The following table provides information on stock options outstanding and exercisable at June 30, 2018 . Stock Weighted-Average Aggregate Weighted-Average Outstanding 6,057 5.4 $ 89 $ 28.26 Exercisable 4,365 4.4 71 26.77 The Company received cash from the exercise of stock options in the amount of $31 million during the first six months of 2018, compared with $39 million in the first six months of 2017. The tax benefit realized as a result of stock option exercises and restricted stock releases was $14 million in the first six months of 2018, compared with $20 million in the first six months of 2017. As of June 30, 2018 , total compensation cost not yet recognized in the Company's financial statements related to restricted stock awards was $54 million , of which $26 million ( 826 thousand shares) was related to restricted stock awards with a performance-based vesting condition. The Company expects to recognize these amounts over a weighted-average period of approximately 1.3 years. There are no other contractual terms covering restricted stock awards once vested. The following table summarizes restricted stock activity during the six -month period ended June 30 . (In thousands of shares) Shares Weighted-Average Grant-Date Fair Value Per Share Restricted stock at December 31, 2017 3,635 $ 32.40 Granted in 2018 993 44.10 Canceled in 2018 (69 ) 33.38 Vested in 2018 (1,062 ) 31.69 Restricted stock at June 30, 2018 3,497 $ 35.91 In February 2018, the Company granted 432 thousand performance-based stock awards, which are contingent on the achievement of the Company's financial performance metrics and its market-based conditions. On the date of grant, the Company estimated the fair value of restricted stock awards with market-based conditions using a Monte Carlo simulation model. The model discounts the value of the stock at the assumed vesting date based on the risk-free interest rate. Based on estimates of actual performance versus the vesting thresholds, the calculated fair value percentage pay-out estimate will be updated each quarter. The Company uses third-party analyses to assist in developing the assumptions used in, as well as calibrating, a Monte Carlo simulation model. The Company is responsible for determining the assumptions used in estimating the fair value of its share-based payment awards. For additional information on the Company's long-term share-based compensation plans and the types of share-based awards, see Note 12 of the Notes to the Consolidated Financial Statements included in the 2017 Annual Report.

BENEFIT PLANS

BENEFIT PLANS	6 Months Ended
	Jun. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
BENEFIT PLANS	BENEFIT PLANS The Company has funded defined benefit plans in Japan and the United States, however the U.S. plan was frozen to new participants effective October 1, 2013. The Company also maintains non-qualified, unfunded supplemental retirement plans that provide defined pension benefits in excess of limits imposed by federal tax law for certain Japanese, U.S. and former employees, however the U.S. plan was frozen to new participants effective January 1, 2015. U.S. employees who are not participants in the defined benefit plan receive a nonelective 401(k) employer contribution. The Company provides certain health care benefits for eligible U.S. retired employees, their beneficiaries and covered dependents ("other postretirement benefits"). The health care plan is contributory and unfunded. Effective January 1, 2014, employees eligible for benefits included the following: (1) active employees whose age plus service, in years, equaled or exceeded 80 (rule of 80 ); (2) active employees who were age 55 or older and have met the 15 years of service requirement; (3) active employees who would meet the rule of 80 in the next five years ; (4) active employees who were age 55 or older and who would meet the 15 years of service requirement within the next five years ; and (5) current retirees. For certain employees and former employees, additional coverage is provided for all medical expenses for life. Pension and other postretirement benefit expenses are included in acquisition and operating expenses in the consolidated statement of earnings, which includes other components of net periodic pension cost and postretirement costs (other than service costs) of $7 million and $10 million for the three-month periods and $13 million and $15 million for the six-month periods ended June 30, 2018 and 2017 , respectively. Total net periodic cost includes the following components: Three Months Ended June 30, Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2018 2017 2018 2017 2018 2017 Components of net periodic Service cost $ 5 $ 4 $ 7 $ 6 $ 0 $ 0 Interest cost 1 2 8 8 1 1 Expected return on plan (1 ) (1 ) (6 ) (5 ) 0 0 Amortization of net actuarial 0 1 4 4 0 0 Amortization of prior service 0 0 0 0 0 0 Net periodic (benefit) cost $ 5 $ 6 $ 13 $ 13 $ 1 $ 1 Six Months Ended June 30, Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2018 2017 2018 2017 2018 2017 Components of net periodic Service cost $ 10 $ 9 $ 14 $ 12 $ 0 $ 0 Interest cost 3 3 17 16 1 1 Expected return on plan (3 ) (2 ) (13 ) (11 ) 0 0 Amortization of net actuarial 0 1 8 7 0 0 Amortization of prior service 0 0 0 0 0 0 Net periodic (benefit) cost $ 10 $ 11 $ 26 $ 24 $ 1 $ 1 During the six months ended June 30, 2018 , Aflac Japan contributed approximately $14 million (using the weighted-average yen/dollar exchange rate for the six -month period ending June 30, 2018 ) to the Japanese funded defined benefit plan, and Aflac U.S. contributed $10 million to the U.S. funded defined benefit plan. As a result of U.S. tax reform legislation enacted in December 2017, the Company announced it would make a one-time contribution of $500 to the U.S. 401(k) plan to all employees active on December 31, 2017. This contribution was made by January 31, 2018. The Company also announced that it would increase its matching contributions to 100% of each employee's contributions which were not in excess of 4% of the employee's annual cash compensation. This increase became effective on January 1, 2018. For additional information regarding the Company's Japanese and U.S. benefit plans, see Note 14 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report.

COMMITMENTS AND CONTINGENT LIAB

COMMITMENTS AND CONTINGENT LIABILITIES	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENT LIABILITIES	COMMITMENTS AND CONTINGENT LIABILITIES The Company is a defendant in various lawsuits considered to be in the normal course of business. Members of the Company's senior legal and financial management teams review litigation on a quarterly and annual basis. The final results of any litigation cannot be predicted with certainty. Although some of this litigation is pending in states where large punitive damages, bearing little relation to the actual damages sustained by plaintiffs, have been awarded in recent years, the Company believes the outcome of pending litigation will not have a material adverse effect on its financial position, results of operations, or cash flows. See Note 3 of the Notes to the Consolidated Financial Statements for details on certain investment commitments. Guaranty Fund Assessments The United States insurance industry has a policyholder protection system that is monitored and regulated by state insurance departments. These life and health insurance guaranty associations are state entities (in all 50 states as well as Puerto Rico and the District of Columbia) created to protect policyholders of an insolvent insurance company. All insurance companies (with limited exceptions) licensed to sell life or health insurance in a state must be members of that state’s guaranty association. Under state guaranty association laws, certain insurance companies can be assessed (up to prescribed limits) for certain obligations to the policyholders and claimants of impaired or insolvent insurance companies that write the same line or similar lines of business. In 2009, the Pennsylvania Insurance Commissioner placed long-term care insurer Penn Treaty Network America Insurance Company and its subsidiary American Network Insurance Company (collectively referred to as Penn Treaty), neither of which is affiliated with Aflac, in rehabilitation and petitioned a state court for approval to liquidate Penn Treaty. A final order of liquidation was granted by a recognized judicial authority on March 1, 2017, and as a result, Penn Treaty is in the process of liquidation. The Company estimated and recognized the impact of its share of guaranty fund assessments resulting from the liquidation using a discounted rate of 4.25% . The Company recognized a discounted liability for the assessments of $62 million (undiscounted $94 million ), offset by discounted premium tax credits of $48 million (undiscounted $74 million ), for a net $14 million impact to net income in the quarter ended March 31, 2017. The Company paid a majority of these assessments by March 31, 2018, and a majority of the tax credits will be realized over the next four years. The Company used the cost estimate provided as of the liquidation date by the National Organization of Life and Health Guaranty Associations (NOLHGA) to calculate its estimated assessments and tax credits. Guaranty fund assessments for the six-month period ended June 30, 2018 were immaterial.

SUMMARY OF SIGNIFICANT ACCOUN21

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business Aflac Incorporated (the Parent Company) and its subsidiaries (collectively, the Company) primarily sell supplemental health and life insurance in the United States and Japan. The Company's insurance business is marketed and administered through American Family Life Assurance Company of Columbus (Aflac) in the United States (Aflac U.S.) and, effective April 1, 2018, through Aflac Life Insurance Japan Ltd. in Japan (Aflac Japan). Prior to April 1, 2018, the Company's insurance business was marketed in Japan as a branch of Aflac. American Family Life Assurance Company of New York (Aflac New York) is a wholly owned subsidiary of Aflac. Most of Aflac's policies are individually underwritten and marketed through independent agents. Additionally, Aflac U.S. markets and administers group products through Continental American Insurance Company (CAIC), branded as Aflac Group Insurance. The Company's insurance operations in the United States and Japan service the two markets for the Company's insurance business. Aflac Japan's revenues, including realized gains and losses on its investment portfolio, accounted for 70% and 69% of the Company's total revenues in the six -month periods ended June 30, 2018 and 2017 , respectively. The percentage of the Company's total assets attributable to Aflac Japan was 85% at June 30, 2018 , compared with 83% at December 31, 2017 . Basis of Presentation The Company prepares its financial statements in accordance with U.S. generally accepted accounting principles (GAAP). These principles are established primarily by the Financial Accounting Standards Board (FASB). In these Notes to the Consolidated Financial Statements, references to U.S. GAAP issued by the FASB are derived from the FASB Accounting Standards Codification TM (ASC). The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates based on currently available information when recording transactions resulting from business operations. The most significant items on the Company's balance sheet that involve a greater degree of accounting estimates and actuarial determinations subject to changes in the future are the valuation of investments and derivatives, deferred policy acquisition costs (DAC), liabilities for future policy benefits and unpaid policy claims, and income taxes. These accounting estimates and actuarial determinations are sensitive to market conditions, investment yields, mortality, morbidity, commission and other acquisition expenses, and terminations by policyholders. As additional information becomes available, or actual amounts are determinable, the recorded estimates will be revised and reflected in operating results. Although some variability is inherent in these estimates, the Company believes the amounts provided are adequate. The unaudited consolidated financial statements include the accounts of the Parent Company, its subsidiaries and those entities required to be consolidated under applicable accounting standards. All material intercompany accounts and transactions have been eliminated. In the opinion of management, the accompanying unaudited consolidated financial statements of the Company contain all adjustments, consisting of normal recurring accruals, which are necessary to fairly present the consolidated balance sheets as of June 30, 2018 , and December 31, 2017 , the consolidated statements of earnings and comprehensive income (loss) for the three- and six -month periods ended June 30, 2018 and 2017, and the consolidated statements of shareholders' equity and cash flows for the six -month periods ended June 30, 2018 and 2017 . Results of operations for interim periods are not necessarily indicative of results for the entire year. As a result, these financial statements should be read in conjunction with the financial statements and notes thereto included in the Company's annual report on Form 10-K for the year ended December 31, 2017 ( 2017 Annual Report). Stock split: On February 13, 2018, the Board of Directors of the Parent Company declared a two -for-one stock split of the Company’s common stock in the form of a 100% stock dividend payable on March 16, 2018 to shareholders of record at the close of business on March 2, 2018. The stock split was payable in the form of one additional common stock share for every share of common stock held. All equity and share-based data, including the number of shares outstanding and per share amounts, have been adjusted to reflect the stock split for all periods presented in this Quarterly Report on Form 10-Q.
Reclassifications	Reclassifications : Certain reclassifications have been made to prior-year amounts to conform to current-year reporting classifications. These reclassifications had no impact on net earnings or total shareholders' equity. Perpetual securities have been reclassified in prior periods from a separate line item to fixed maturity securities to conform to current period reporting classifications. This reclassification had no impact on net earnings or total shareholder’s equity.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters Accounting Standards Update (ASU) 2018-03 Technical Corrections and Improvements to Financial Instruments - Overall In February 2018, the FASB issued amendments to clarify certain aspects of the guidance issued in the original Financial Instruments - Overall - Recognition and Measurement pronouncement summarized below. Specifically, for entities who have chosen the measurement alternative approach for equity securities without readily determinable fair values, the amendments clarify that entities may change from a measurement alternative approach to a fair value method through an irrevocable election that would apply to a specific equity security and all identical or similar investments of the same issuer; entities should use an observable price at the date of the transaction rather than reporting date for the measurement alternative calculation; and insurance companies should use a prospective transition method when applying the measurement alternative. The amendments are effective for public business entities for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years beginning after June 15, 2018. All entities may early adopt these amendments for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years, as long as they have adopted the Financial Instruments - Overall - Recognition and Measurement guidance discussed below. Early adopted as of January 1, 2018 The adoption of this guidance did not have a significant impact on the Company’s financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2018-02 Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued amendments which allow a reclassification from accumulated other comprehensive income (AOCI) to retained earnings of the effects of the change in the U.S. federal income tax rate resulting from the Tax Cuts and Jobs Act (Tax Act) on the gross deferred tax amounts and the corresponding valuation allowances related to items remaining in AOCI. The amendments eliminate the stranded tax effects resulting from the Tax Act and also require certain disclosures about the reclassified tax effects. The amendments are effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Public business entities may early adopt this guidance in any interim reporting period for which financial statements have not yet been issued. The amendments should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Act is recognized. Early adopted as of January 1, 2018 The amounts reclassified from AOCI to retained earnings include the income tax effects of the change in the federal corporate tax rate enacted by the Tax Act. The Company’s policy is to follow the portfolio approach for releasing income tax effects from AOCI. The adoption of this guidance resulted in an increase to beginning 2018 AOCI of $374 million with a corresponding decrease to beginning 2018 retained earnings as of January 1, 2018. ASU 2017-09 Compensation - Stock Compensation: Scope of Modification Accounting In May 2017, the FASB issued amendments to provide guidance clarifying when changes to the terms or conditions of a share-based payment award must be accounted for as modifications. An entity should apply modification accounting if the fair value, vesting conditions or classification of the award (as an equity instrument or liability instrument) changes as a result of the change in terms or conditions of the award. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-07 Compensation - Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost In March 2017, the FASB issued amendments requiring that an employer report the service cost component of net periodic pension cost and net periodic postretirement benefit cost in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net periodic pension cost and net periodic postretirement benefit cost are required to be presented in the income statement separately from the service cost component and outside a subtotal of income from operations, if one is presented. If a separate line item or items are used to present the other components of net benefit cost, that line item or items must be appropriately described. If a separate line item or items are not used, the line item or items used in the income statement to present the other components of net benefit cost must be disclosed. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2017-05 Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets: Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets In February 2017, the FASB issued amendments that clarify the scope and accounting guidance for the derecognition of a nonfinancial asset or a financial asset that meets the definition of an "in substance nonfinancial asset." The amendments define an "in substance nonfinancial asset" and provide additional accounting guidance for partial sales of nonfinancial assets. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-01 Business Combinations: Clarifying the Definition of a Business In January 2017, the FASB issued amendments clarifying when a set of assets and activities is a business. The amendments provide a screen to exclude transactions where substantially all the fair value of the transferred set is concentrated in a single asset, or group of similar assets, from being evaluated as a business. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-18 Statement of Cash Flows: Restricted Cash In November 2016, the FASB issued amendments requiring that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, statements of cash flows, or disclosures. ASU 2016-16 Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued amendments that require an entity to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-15 Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued amendments that provide guidance on eight specific statement of cash flows classification issues. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, statements of cash flows, or disclosures. ASU 2016-01 Financial Instruments - Overall: Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, the FASB issued guidance to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. The main provisions of this guidance require certain equity investments to be measured at fair value with changes in fair value recognized in net earnings; separate presentation in other comprehensive income for changes in fair value of financial liabilities measured under the fair value option that are due to instrument-specific credit risk; and changes in disclosures associated with the fair value of financial instruments. The guidance also clarifies that entities should evaluate the need for a valuation allowance on a deferred tax asset (DTA) related to available-for-sale (AFS) securities in combination with the entity's other DTAs. January 1, 2018 The Company recorded a cumulative effect adjustment with an increase to beginning 2018 retained earnings and a decrease to beginning 2018 AOCI of $148 million, net of taxes. Standard Description Date of Adoption Effect on Financial Statements or Other Significant Matters ASU 2014-09 Revenue from Contracts with Customers In May 2014, the FASB issued updated guidance that affects any entity that either enters into contracts with customers to transfer goods or services or enters into contracts for the transfer of nonfinancial assets unless those contracts are within the scope of other standards (e.g., insurance contracts or lease contracts). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. January 1, 2018 The adoption of this guidance did not have a significant impact on the Company's financial position, results of operations, or disclosures.
Description of Accounting Pronouncements Pending Adoption	Accounting Pronouncements Pending Adoption Standard Description Effect on Financial Statements or Other Significant Matters ASU 2018-10 Codification Improvements to Topic 842, Leases In July 2018, the FASB issued guidance which clarifies, corrects errors in, or makes minor improvements to the Codification related to ASU 2016-02, Leases (Topic 842). The amendments in this ASU affect narrow aspects of the guidance issued in the amendments to ASU 2016-02, including but not limited to, Residual Value Guarantees, Rate Implicit in the Lease, Lessee Reassessment of Lease Classification and Variable Lease Payments that Depend on an Index or a Rate. Amendments within this ASU follow the effective dates of Topic 842, which are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. The adoption of this guidance is not expected to have a significant impact on the Company’s financial position, results of operations, or disclosures. ASU 2018-01 Leases: Land Easement Practical Expedient for Transition to Topic 842 In January 2018, the FASB issued guidance which provides an entity with the option to elect a transition practical expedient to not evaluate, under Topic 842, land easements that exist or expired before the entity's adoption of Topic 842 and that were not previously accounted for as leases under Topic 840. The amendments clarify that new or modified land easements should be evaluated under the new leases standard once an entity has adopted the new standard. The amendments are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-12 Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities In August 2017, the FASB issued guidance which improves and simplifies the accounting rules around hedge accounting and will create more transparency around how economic results are presented on financial statements. Issues addressed in this new guidance include: 1) risk component hedging, 2) accounting for the hedged item in fair value hedges of interest rate risk, 3) recognition and presentation of the effects of hedging instruments, and 4) amounts excluded from the assessment of hedge effectiveness. The amendments are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted in any interim period after issuance of the guidance. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. Standard Description Effect on Financial Statements or Other Significant Matters ASU 2017-08 Receivables - Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities In March 2017, the FASB issued amendments to shorten the amortization period for certain callable debt securities held at a premium. Specifically, the amendments require the premium to be amortized to the earliest call date. The amendments do not require an accounting change for securities held at a discount. The amendments are effective for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2017-04 Intangibles - Goodwill and Other: Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued amendments simplifying the subsequent measurement of goodwill. An entity, under this update, is no longer required to perform a hypothetical purchase price allocation to measure goodwill impairment. Instead, the entity should perform its annual or interim goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. The amendments are effective for public business entities that are SEC filers for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for any goodwill impairment tests performed on testing dates after January 1, 2017. The adoption of this guidance is not expected to have a significant impact on the Company's financial position, results of operations, or disclosures. ASU 2016-13 Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued amendments that require a financial asset (or a group of financial assets) measured on an amortized cost basis to be presented net of an allowance for credit losses in order to reflect the amount expected to be collected on the financial asset(s). The measurement of expected credit losses is amended by replacing the incurred loss impairment methodology in current U.S. GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform about a credit loss. Credit losses on available-for-sale debt securities will continue to be measured in a manner similar to current U.S. GAAP; however, the amendments require that credit losses be presented as an allowance rather than as a write-down. Other amendments include changes to the balance sheet presentation and interest income recognition of purchased financial assets with a more-than-insignificant amount of credit deterioration since origination (PCD financial assets). The amendments are effective for public companies for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Companies may early adopt this guidance as of the fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The amendments will be adopted following a modified-retrospective approach resulting in a cumulative effect adjustment in retained earnings as of the beginning of the year of adoption. Two exceptions to this adoption method are for PCD financial assets and debt securities for which other-than-temporary impairment (OTTI) will have been recognized before the effective date. Loans purchased with credit deterioration accounted for under current U.S. GAAP as "purchased credit impaired" (PCI) financial assets will be classified as PCD financial assets at transition and PCD guidance will be applied prospectively. Debt securities that have experienced OTTI before the effective date will follow a prospective adoption method which allows an entity to maintain the same amortized cost basis before and after the effective date. The Company has identified certain financial instruments in scope of this guidance to include certain fixed maturity securities, loan and loan receivables and reinsurance recoverables (See Notes 3 and 7 for current balances of instruments in scope). The Company is continuing its progress towards updating its credit loss projection models and accounting systems in order to comply with the required changes in measurement of credit losses. The Company currently expects loans and loan receivables and held-to-maturity fixed maturity securities to be the asset classes most significantly impacted upon adoption of the guidance. The Company continues to evaluate the impact of adoption of this guidance on its financial position, results of operations, and disclosures. Standard Description Effect on Financial Statements or Other Significant Matters ASU 2016-02 Leases In February 2016, the FASB issued updated guidance for accounting for leases. Per the amendments, lessees will be required to recognize all leases on the balance sheet with the exception of short-term leases. A lease liability will be recorded for the obligation of a lessee to make lease payments arising from a lease. A right-of-use asset will be recorded which represents the lessee’s right to control the use of a specified asset for a lease term. Under the new guidance, lessor accounting is largely unchanged. The amendments are effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. The Company has identified certain operating leases in scope of this guidance to include office space and equipment leases (See Note 15 of the Notes to the Consolidated Financial Statements in the 2017 Annual Report for current balances of leases in scope). The leases within scope of this guidance will increase the Company's right-of-use assets and lease liabilities recorded on its statement of financial position, however the Company estimates leases within scope of the guidance to represent less than 1% of its total assets as of June 30, 2018. The Company estimates that the adoption of this guidance will not have a significant impact on its financial position, results of operations, or disclosures.

BUSINESS SEGMENT INFORMATION (T

BUSINESS SEGMENT INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Reconciliation of Revenue from Segments to Consolidated	Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Revenues: Aflac Japan: Net earned premiums $ 3,227 $ 3,222 $ 6,490 $ 6,416 Net investment income, less amortized hedge costs (1) 606 557 1,194 1,115 Other income 11 10 22 20 Total Aflac Japan 3,844 3,789 7,706 7,551 Aflac U.S.: Net earned premiums 1,426 1,388 2,853 2,778 Net investment income 182 180 357 358 Other income 2 2 4 3 Total Aflac U.S. 1,610 1,570 3,214 3,139 Corporate and other (2) 85 70 164 138 Total adjusted revenues 5,539 5,429 11,084 10,828 Realized investment gains (losses) (1),(2) 50 (1 ) (30 ) (91 ) Total revenues $ 5,589 $ 5,428 $ 11,054 $ 10,737 (1) Amortized hedge costs related to hedging U.S. dollar-denominated investments held in Aflac Japan were $55 and $56 for the three- month periods and $110 and $108 for the six -month periods ended June 30, 2018 , and 2017 , respectively, and have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing segment operations. (2) Amortized hedge costs in Aflac Japan were partially offset by derivatives entered into as part of corporate activities and resulted in a benefit of $7 for the three-month period and $9 for the six -month period ended June 30, 2018 , respectively, which has been reclassified from realized investment gains (losses) and reported as an increase in net investment income when analyzing operations.
Reconciliation of Adjusted Profit (Loss) from Segments to Consolidated	Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Pretax earnings: Aflac Japan (1) $ 836 $ 791 $ 1,654 $ 1,560 Aflac U.S. 340 330 677 640 Corporate and other (2) (38 ) (48 ) (84 ) (100 ) Pretax adjusted earnings 1,138 1,073 2,247 2,100 Realized investment gains (losses) (1),(2),(3) 35 (19 ) (63 ) (128 ) Other income (loss) (42 ) (9 ) (70 ) (28 ) Total earnings before income taxes $ 1,131 $ 1,045 $ 2,114 $ 1,944 Income taxes applicable to pretax adjusted earnings $ 303 $ 342 $ 592 $ 694 Effect of foreign currency translation on after-tax 7 (9 ) 29 (3 ) (1) Amortized hedge costs related to hedging U.S. dollar-denominated investments held in Aflac Japan were $55 and $56 for the three- month periods and $110 and $108 for the six -month periods ended June 30, 2018 , and 2017 , respectively, and have been reclassified from realized investment gains (losses) and reported as a deduction from pretax adjusted earnings when analyzing segment operations. (2) Amortized hedge costs in Aflac Japan were partially offset by derivatives entered into as part of corporate activities and resulted in a benefit of $7 for the three-month period and $9 for the six -month period ended June 30, 2018 which has been reclassified from realized investment gains (losses) and reported as an increase in pretax adjusted earnings when analyzing operations. (3) Excluding a gain of $17 and $20 for the three-month periods and $33 and $41 for the six -month periods ended June 30, 2018 , and 2017 , respectively, related to the interest rate component of the change in fair value of foreign currency swaps on notes payable which is included in adjusted earnings when analyzing segment operations
Reconciliation of Assets from Segment to Consolidated	Assets were as follows: (In millions) June 30, December 31, Assets: Aflac Japan $ 120,228 $ 114,402 Aflac U.S. 19,588 19,893 Corporate and other 2,170 2,922 Total assets $ 141,986 $ 137,217

INVESTMENTS (Tables)

INVESTMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Securities, Available-for-sale	The amortized cost for the Company's investments in debt securities, the cost for equity securities and the fair values of these investments are shown in the following tables. June 30, 2018 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value Fixed maturity securities: (1) Yen-denominated: Japan government and agencies $ 31,384 $ 3,742 $ 150 $ 34,976 Municipalities 375 32 9 398 Mortgage- and asset-backed securities 156 22 0 178 Public utilities 1,663 313 3 1,973 Sovereign and supranational 1,263 188 30 1,421 Banks/financial institutions 5,399 651 126 5,924 Other corporate 4,298 688 6 4,980 Total yen-denominated 44,538 5,636 324 49,850 U.S. dollar-denominated: U.S. government and agencies 133 8 1 140 Municipalities 1,396 135 1 1,530 Mortgage- and asset-backed securities 162 8 1 169 Public utilities 4,939 555 103 5,391 Sovereign and supranational 264 58 0 322 Banks/financial institutions 2,871 417 30 3,258 Other corporate 24,632 1,569 980 25,221 Total U.S. dollar-denominated 34,397 2,750 1,116 36,031 Total securities available for sale $ 78,935 (1) $ 8,386 $ 1,440 $ 85,881 (1) (1) Includes perpetual securities ( $1,446 at amortized cost and $1,612 at fair value)
Held-to-maturity Securities	December 31, 2017 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 21,331 $ 5,160 $ 0 $ 26,491 Municipalities 357 105 0 462 Mortgage- and asset-backed securities 26 1 0 27 Public utilities 3,300 398 0 3,698 Sovereign and supranational 1,523 312 0 1,835 Banks/financial institutions 2,206 190 9 2,387 Other corporate 2,687 485 0 3,172 Total yen-denominated 31,430 6,651 9 38,072 Total securities held to maturity $ 31,430 $ 6,651 $ 9 $ 38,072 June 30, 2018 (In millions) Cost or Gross Gross Fair Securities held to maturity, carried at amortized cost: Fixed maturity securities: Yen-denominated: Japan government and agencies $ 21,808 $ 5,409 $ 0 $ 27,217 Municipalities 363 111 0 474 Mortgage- and asset-backed securities 16 1 0 17 Public utilities 3,236 317 1 3,552 Sovereign and supranational 1,557 286 0 1,843 Banks/financial institutions 1,532 178 10 1,700 Other corporate 2,747 406 0 3,153 Total yen-denominated 31,259 6,708 11 37,956 Total securities held to maturity $ 31,259 $ 6,708 $ 11 $ 37,956
Equity securities, FV-NI	June 30, 2018 (In millions) Fair Equity securities, carried at fair value through net earnings: Equity securities: (1) Yen-denominated $ 712 U.S. dollar-denominated 391 Total equity securities $ 1,103 (1) (1) Includes perpetual securities ( $69 at fair value)
Available-for-sale Securities	December 31, 2017 (In millions) Cost or Gross Gross Fair Securities available for sale, carried at fair value: Fixed maturity securities: (1) Yen-denominated: Japan government and agencies $ 27,980 $ 3,363 $ 271 $ 31,072 Municipalities 314 28 12 330 Mortgage- and asset-backed securities 242 29 0 271 Public utilities 1,635 352 6 1,981 Sovereign and supranational 1,380 190 1 1,569 Banks/financial institutions 4,742 811 53 5,500 Other corporate 4,085 809 7 4,887 Total yen-denominated 40,378 5,582 350 45,610 U.S dollar-denominated: U.S. government and agencies 146 13 1 158 Municipalities 872 168 0 1,040 Mortgage- and asset-backed securities 161 12 0 173 Public utilities 5,116 884 27 5,973 Sovereign and supranational 267 73 0 340 Banks/financial institutions 2,808 633 8 3,433 Other corporate 25,384 2,620 418 27,586 Total U.S. dollar-denominated 34,754 4,403 454 38,703 Total securities available for sale $ 75,132 (1) $ 9,985 $ 804 $ 84,313 (1) (1) Includes perpetual securities ( $1,462 at amortized cost and $1,789 at fair value) December 31, 2017 (In millions) Fair Equity securities, carried at fair value: Equity securities: Yen-denominated $ 695 U.S. dollar-denominated 328 Total equity securities $ 1,023
Investments Classified by Contractual Maturity Date	The contractual and economic maturities of the Company's investments in fixed maturity securities at June 30, 2018 , were as follows: (In millions) Amortized Fair Available for sale: (1) Due in one year or less $ 348 $ 359 Due after one year through five years 3,910 4,070 Due after five years through 10 years 11,813 11,912 Due after 10 years 62,547 69,193 Mortgage- and asset-backed securities 317 347 Total fixed maturity securities available for sale $ 78,935 $ 85,881 Held to maturity: Due in one year or less $ 498 $ 505 Due after one year through five years 353 366 Due after five years through 10 years 1,585 1,715 Due after 10 years 28,807 35,353 Mortgage- and asset-backed securities 16 17 Total fixed maturity securities held to maturity $ 31,259 $ 37,956 (1) Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
Investment Exposures Exceeding Ten Percent Shareholders Equity	Investment exposures that individually exceeded 10% of shareholders' equity were as follows: June 30, 2018 December 31, 2017 (In millions) Credit Amortized Fair Credit Amortized Fair Japan National Government (1) A+ $51,881 $60,734 A $48,399 $56,532 (1) Japan Government Bonds (JGBs) or JGB-backed securities
Gain (Loss) on Investments	Information regarding pretax realized gains and losses from investments is as follows: Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Realized investment gains (losses): Fixed maturity securities: (1) Available for sale: Gross gains from sales $ 12 $ 10 $ 22 $ 22 Gross losses from sales (71 ) (8 ) (73 ) (19 ) Foreign exchange gains (losses) 29 (18 ) 24 (50 ) Other-than-temporary impairment losses (2 ) (1 ) (2 ) (4 ) Total fixed maturity securities (32 ) (17 ) (29 ) (51 ) Equity securities (1),(2) 18 15 (3) (28 ) 34 (3) Loan loss reserves (3 ) (2 ) (10 ) (3 ) Derivatives and other: Derivative gains (losses) (172 ) (51 ) (28 ) (103 ) Foreign currency gains (losses) 192 (1 ) (36 ) (73 ) Total derivatives and other 20 (52 ) (64 ) (176 ) Total realized investment gains (losses) $ 3 $ (56 ) $ (131 ) $ (196 ) (1) Includes perpetual securities (2) See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments. (3) Includes impairments of $6 for the three-month period and $12
Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities	The net effect on shareholders’ equity of unrealized gains and losses from investment securities was as follows: (In millions) June 30, 2018 December 31, Unrealized gains (losses) on securities available for sale $ 6,946 $ 9,358 Deferred income taxes (2,110 ) (3,394 ) Shareholders’ equity, unrealized gains (losses) on investment securities $ 4,836 $ 5,964 See Note 1 for discussion of the accounting treatment of tax on amounts recorded in accumulated other comprehensive income pursuant to the Tax Act and for the adoption of accounting guidance on January 1, 2018 related to financial instruments.
Investments Gross Unrealized Loss Aging	The following tables show the fair values and gross unrealized losses of the Company's available-for-sale and held-to-maturity investments that were in an unrealized loss position, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position. June 30, 2018 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: (1) U.S. government and U.S. dollar-denominated $ 78 $ 1 $ 74 $ 1 $ 4 $ 0 Japan government and Yen-denominated 3,647 150 0 0 3,647 150 Municipalities: U.S. dollar-denominated 261 1 261 1 0 0 Yen-denominated 137 9 13 0 124 9 Mortgage- and asset- U.S. dollar-denominated 86 1 71 1 15 0 Public utilities: U.S. dollar-denominated 1,664 103 1,200 52 464 51 Yen-denominated 268 4 180 1 88 3 Sovereign and supranational: U.S. dollar-denominated 13 0 13 0 0 0 Yen-denominated 286 30 286 30 0 0 Banks/financial institutions: U.S. dollar-denominated 696 30 561 20 135 10 Yen-denominated 2,344 136 1,478 50 866 86 Other corporate: U.S. dollar-denominated 13,044 980 8,391 362 4,653 618 Yen-denominated 409 6 294 4 115 2 Total $ 22,933 $ 1,451 $ 12,822 $ 522 $ 10,111 $ 929 (1) Includes perpetual securities December 31, 2017 Total Less than 12 months 12 months or longer (In millions) Fair Unrealized Fair Unrealized Fair Unrealized Fixed maturity securities: (1) U.S. government and U.S. dollar-denominated $ 74 $ 1 $ 74 $ 1 $ 0 $ 0 Japan government and Yen-denominated 5,255 271 1,264 9 3,991 262 Municipalities: Yen-denominated 129 12 10 0 119 12 Public utilities: U.S. dollar-denominated 785 27 221 3 564 24 Yen-denominated 83 6 0 0 83 6 Sovereign and supranational: Yen-denominated 309 1 309 1 0 0 Banks/financial institutions: U.S. dollar-denominated 362 8 316 5 46 3 Yen-denominated 1,507 62 394 4 1,113 58 Other corporate: U.S. dollar-denominated 7,741 418 2,839 50 4,902 368 Yen-denominated 440 7 349 4 91 3 Total $ 16,685 $ 813 $ 5,776 $ 77 $ 10,909 $ 736 (1) Includes perpetual securities
Other Investments	The table below reflects the composition of the carrying value for other investments as of the periods presented. (In millions) June 30, 2018 December 31, 2017 Other investments: Transitional real estate loans $ 3,247 $ 1,235 Commercial mortgage loans 966 908 Middle market loans 1,097 859 Policy loans 222 210 Short-term investments 1 57 Other 298 133 Total other investments $ 5,831 $ 3,402
Securities Lending Transactions Accounted for as Secured Borrowings	Details of the Company's securities lending activities were as follows: Securities Lending Transactions Accounted for as Secured Borrowings June 30, 2018 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 30-90 days Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 2,942 353 $ 3,295 Public utilities 13 0 0 13 Banks/financial institutions 60 0 0 60 Other corporate 335 0 0 335 Equity securities 9 0 0 9 Total borrowings $ 417 $ 2,942 $ 353 $ 3,712 Gross amount of recognized liabilities for securities lending transactions $ 3,712 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 0 (1) These securities are pledged as collateral under the Company's U.S. securities lending program and can be called at its discretion; therefore, they are classified as Overnight and Continuous. Securities Lending Transactions Accounted for as Secured Borrowings December 31, 2017 Remaining Contractual Maturity of the Agreements (In millions) Overnight (1) Up to 30 Total Securities lending transactions: Fixed maturity securities: Japan government and agencies $ 0 $ 49 $ 49 Public utilities 73 0 73 Banks/financial institutions 54 0 54 Other corporate 415 0 415 Equity securities 15 0 15 Total borrowings $ 557 $ 49 $ 606 Gross amount of recognized liabilities for securities lending transactions $ 606 Amounts related to agreements not included in offsetting disclosure in Note 4 $ 0 (1) These securities are pledged as collateral under the Company's U.S. securities lending program and can be called at its discretion; therefore, they are classified as Overnight and Continuous.
Variable Interest Entity, Consolidated
Investments in Variable Interest Entities	VIEs - Consolidated The following table presents the cost or amortized cost, fair value and balance sheet caption in which the assets and liabilities of consolidated VIEs are reported. Investments in Consolidated Variable Interest Entities June 30, 2018 December 31, 2017 (In millions) Cost or Amortized Fair Cost or Amortized Fair Assets: Fixed maturity securities, available for sale (1) $ 4,492 $ 5,202 $ 4,538 $ 5,509 Equity securities 755 755 606 753 Other investments (2) 4,586 4,577 2,341 2,328 Other assets (3) 202 202 151 151 Total assets of consolidated VIEs $ 10,035 $ 10,736 $ 7,636 $ 8,741 Liabilities: Other liabilities (3) $ 92 $ 92 $ 128 $ 128 Total liabilities of consolidated VIEs $ 92 $ 92 $ 128 $ 128 (1) Includes perpetual securities (2) Consists of TREs, CMLs, MMLs, and alternative investments in limited partnerships (3) Consists entirely of derivatives
Variable Interest Entity, Not Consolidated
Investments in Variable Interest Entities	VIEs-Not Consolidated The table below reflects the amortized cost, fair value and balance sheet caption in which the Company's investment in VIEs not consolidated are reported. Investments in Variable Interest Entities Not Consolidated June 30, 2018 December 31, 2017 (In millions) Amortized Fair Amortized Fair Assets: Fixed maturity securities, available for sale (1) $ 4,870 $ 5,358 $ 5,004 $ 5,724 Fixed maturity securities, held to maturity 2,469 2,795 2,549 2,929 Other investments 106 106 55 55 Total investments in VIEs not consolidated $ 7,445 $ 8,259 $ 7,608 $ 8,708 (1) Includes perpetual securities

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	June 30, 2018 December 31, 2017 (In millions) Asset Liability Asset Liability Hedge Designation/ Derivative Notional Fair Value Fair Value Notional Fair Value Fair Value Cash flow hedges: Foreign currency swaps $ 75 $ 1 $ (4 ) $ 75 $ 0 $ (8 ) Total cash flow hedges 75 1 (4 ) 75 0 (8 ) Fair value hedges: Foreign currency forwards 3,310 17 (3 ) 7,640 2 (221 ) Foreign currency options 9,225 0 (5 ) 7,670 0 (2 ) Total fair value hedges 12,535 17 (8 ) 15,310 2 (223 ) Net investment hedge: Foreign currency forwards 0 0 0 5 0 0 Foreign currency options 0 0 0 434 12 (1 ) Total net investment hedge 0 0 0 439 12 (1 ) Non-qualifying strategies: Foreign currency swaps 5,390 320 (223 ) 5,386 296 (189 ) Foreign currency forwards 10,410 119 (132 ) 3,683 20 (53 ) Foreign currency options 303 0 0 770 0 0 Credit default swaps 90 0 0 88 1 0 Total non-qualifying strategies 16,193 439 (355 ) 9,927 317 (242 ) Total derivatives $ 28,803 $ 457 $ (367 ) $ 25,751 $ 331 $ (474 ) Balance Sheet Location Other assets $ 17,559 $ 457 $ 0 $ 10,948 $ 331 $ 0 Other liabilities 11,244 0 (367 ) 14,803 0 (474 ) Total derivatives $ 28,803 $ 457 $ (367 ) $ 25,751 $ 331 $ (474 )
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position, Location	The following table presents the gains and losses on derivatives and the related hedged items in fair value hedges. Fair Value Hedging Relationships (In millions) Hedging Derivatives Hedged Items Hedging Derivatives Hedged Items Total Gains (Losses) Gains (Losses) Gains (Losses) Ineffectiveness Three Months Ended June 30, 2018: Foreign currency Fixed maturity securities $ (215 ) $ (30 ) $ (185 ) $ 186 $ 1 Foreign currency Fixed maturity securities (2 ) (2 ) 0 0 0 Six Months Ended June 30, 2018: Foreign currency forwards Fixed maturity securities $ 199 $ (69 ) $ 268 $ (278 ) $ (10 ) Foreign currency options Fixed maturity securities (3 ) (3 ) 0 0 0 Three Months Ended June 30, 2017: Foreign currency Fixed maturity and equity securities $ (34 ) $ (50 ) $ 16 $ (15 ) $ 1 Foreign currency options Fixed maturity securities (7 ) (7 ) 0 0 0 Six Months Ended June 30, 2017: Foreign currency forwards Fixed maturity and equity securities $ 307 $ (98 ) $ 405 $ (387 ) $ 18 Foreign currency options Fixed maturity securities 17 6 11 (10 ) 1
Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance	The following table summarizes the impact to realized investment gains (losses) and other comprehensive income (loss) from all derivatives and hedging instruments. Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 (In millions) Realized Investment Other (1) Realized Investment Other (1) Realized Investment Other (1) Realized Investment Other (1) Qualifying hedges: Cash flow hedges: Foreign currency swaps $ 0 $ (2 ) $ 0 $ (2 ) $ 1 $ 4 $ 0 $ 1 Total cash flow hedges 0 (2 ) 0 (2 ) 1 4 0 1 Fair value hedges: Foreign currency forwards (2) (29 ) (49 ) (79 ) (80 ) Foreign currency options (2) (2 ) (7 ) (3 ) 7 Total fair value hedges (31 ) (56 ) (82 ) (73 ) Net investment hedge: Non- derivative hedging instruments 0 55 0 (1 ) 0 (29 ) 0 (18 ) Foreign currency forwards 0 0 0 (19 ) 0 0 0 (28 ) Foreign currency options 0 0 0 31 0 (8 ) 0 8 Total net investment hedge 0 55 0 11 0 (37 ) 0 (38 ) Non-qualifying strategies: Foreign currency swaps 14 34 28 26 Foreign currency forwards (154 ) (29 ) 25 (56 ) Foreign currency options (1 ) 0 0 0 Total non- qualifying strategies (141 ) 5 53 (30 ) Total $ (172 ) $ 53 $ (51 ) $ 9 $ (28 ) $ (33 ) $ (103 ) $ (37 ) (1) Cash flow hedge items are recorded as unrealized gains (losses) on derivatives and net investment hedge items are recorded in the unrealized foreign currency translation gains (losses) line in the consolidated statement of comprehensive income (loss). (2) Impact shown net of effect of hedged items (see Fair Value Hedges section of this Note 4 for further detail)
Fair Value and Notional Amount of Derivatives with Counterparty Credit Risk	The counterparties to these derivatives are financial institutions with the following credit ratings: June 30, 2018 December 31, 2017 (In millions) Notional Amount Asset Derivatives Liability Derivatives Notional Amount Asset Derivatives Liability Derivatives Counterparties' credit rating: AA $ 5,122 $ 78 $ (12 ) $ 4,708 $ 52 $ (37 ) A 23,237 375 (302 ) 20,604 271 (370 ) BBB 444 4 (53 ) 439 8 (67 ) Total $ 28,803 $ 457 $ (367 ) $ 25,751 $ 331 $ (474 )
Offsetting Assets	Offsetting of Financial Assets and Derivative Asset June 30, 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement $ 255 $ 0 $ 255 $ (138 ) $ (32 ) $ (82 ) $ 3 Derivative assets not subject to a master netting agreement or offsetting arrangement 202 202 202 Total derivative assets 457 0 457 (138 ) (32 ) (82 ) 205 Securities lending and similar arrangements 3,638 0 3,638 0 0 (3,638 ) 0 Total $ 4,095 $ 0 $ 4,095 $ (138 ) $ (32 ) $ (3,720 ) $ 205 December 31, 2017 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Assets Gross Amount Offset in Balance Sheet Net Amount of Assets Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Received Net Amount Derivative assets: Derivative assets subject to a master netting agreement or offsetting arrangement $ 180 $ 0 $ 180 $ (82 ) $ 0 $ (98 ) $ 0 Derivative assets not subject to a master netting agreement or offsetting arrangement 151 151 151 Total derivative assets 331 0 331 (82 ) 0 (98 ) 151 Securities lending and similar arrangements 592 0 592 0 0 (592 ) 0 Total $ 923 $ 0 $ 923 $ (82 ) $ 0 $ (690 ) $ 151
Offsetting Liabilities	Offsetting of Financial Liabilities and Derivative Liabilities June 30, 2018 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement $ (276 ) $ 0 $ (276 ) $ 138 $ 73 $ 51 $ (14 ) Derivative liabilities not subject to a master netting agreement or offsetting arrangement (91 ) (91 ) (91 ) Total derivative liabilities (367 ) 0 (367 ) 138 73 51 (105 ) Securities lending and similar arrangements (3,712 ) 0 (3,712 ) 3,638 0 0 (74 ) Total $ (4,079 ) $ 0 $ (4,079 ) $ 3,776 $ 73 $ 51 $ (179 ) December 31, 2017 Gross Amounts Not Offset (In millions) Gross Amount of Recognized Liabilities Gross Amount Offset in Balance Sheet Net Amount of Liabilities Presented in Balance Sheet Financial Instruments Securities Collateral Cash Collateral Pledged Net Amount Derivative liabilities: Derivative liabilities subject to a master netting agreement or offsetting arrangement $ (346 ) $ 0 $ (346 ) $ 82 $ 245 $ 10 $ (9 ) Derivative liabilities not subject to a master netting agreement or offsetting arrangement (128 ) (128 ) (128 ) Total derivative liabilities (474 ) 0 (474 ) 82 245 10 (137 ) Securities lending and similar arrangements (606 ) 0 (606 ) 592 0 0 (14 ) Total $ (1,080 ) $ 0 $ (1,080 ) $ 674 $ 245 $ 10 $ (151 )

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Fair Value Hierarchy, Assets and Liabilities Measured on Recurring Basis	The following tables present the fair value hierarchy levels of the Company's assets and liabilities that are measured and carried at fair value on a recurring basis. June 30, 2018 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: (1) Government and agencies $ 33,591 $ 1,525 $ 0 $ 35,116 Municipalities 0 1,928 0 1,928 Mortgage- and asset-backed securities 0 169 178 347 Public utilities 0 7,258 106 7,364 Sovereign and supranational 0 1,743 0 1,743 Banks/financial institutions 0 9,159 23 9,182 Other corporate 0 30,005 196 30,201 Total fixed maturity securities 33,591 51,787 503 85,881 (1) Equity securities (1) 1,011 75 17 1,103 (1) Other investments 1 0 0 1 Cash and cash equivalents 3,847 0 0 3,847 Other assets: Foreign currency swaps 0 119 202 321 Foreign currency forwards 0 136 0 136 Total other assets 0 255 202 457 Total assets $ 38,450 $ 52,117 $ 722 $ 91,289 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 135 $ 92 $ 227 Foreign currency forwards 0 135 0 135 Foreign currency options 0 5 0 5 Total liabilities $ 0 $ 275 $ 92 $ 367 (1) Includes perpetual securities December 31, 2017 (In millions) Quoted Prices in Significant Significant Total Assets: Securities available for sale, carried at Fixed maturity securities: (1) Government and agencies $ 30,109 $ 1,121 $ 0 $ 31,230 Municipalities 0 1,370 0 1,370 Mortgage- and asset-backed securities 0 269 175 444 Public utilities 0 7,886 68 7,954 Sovereign and supranational 0 1,909 0 1,909 Banks/financial institutions 0 8,908 25 8,933 Other corporate 0 32,327 146 32,473 Total fixed maturity securities 30,109 53,790 414 84,313 (1) Equity securities 1,001 6 16 1,023 Other investments 57 0 0 57 Cash and cash equivalents 3,491 0 0 3,491 Other assets: Foreign currency swaps 0 146 150 296 Foreign currency forwards 0 22 0 22 Foreign currency options 0 12 0 12 Credit default swaps 0 0 1 1 Total other assets 0 180 151 331 Total assets $ 34,658 $ 53,976 $ 581 $ 89,215 Liabilities: Other liabilities: Foreign currency swaps $ 0 $ 69 $ 128 $ 197 Foreign currency forwards 0 274 0 274 Foreign currency options 0 3 0 3 Total liabilities $ 0 $ 346 $ 128 $ 474 (1) Includes perpetual securities
Fair Value Hierarchy Levels of Assets and Liabilities Carried at Cost or Amortized Cost	The following tables present the carrying amount and fair value categorized by fair value hierarchy level for the Company's financial instruments that are not carried at fair value. June 30, 2018 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 21,808 $ 27,209 $ 8 $ 0 $ 27,217 Municipalities 363 0 474 0 474 Mortgage and asset-backed 16 0 0 17 17 Public utilities 3,236 0 3,552 0 3,552 Sovereign and 1,557 0 1,843 0 1,843 Banks/financial institutions 1,532 0 1,700 0 1,700 Other corporate 2,747 0 3,153 0 3,153 Other investments (1) 5,329 0 19 5,297 5,316 Total assets $ 36,588 $ 27,209 $ 10,749 $ 5,314 $ 43,272 Liabilities: Other policyholders’ funds $ 7,140 $ 0 $ 0 $ 7,060 $ 7,060 Notes payable 5,299 0 5,110 270 5,380 Total liabilities $ 12,439 $ 0 $ 5,110 $ 7,330 $ 12,440 (1) Excludes policy loans of $222 and equity method investments of $279 , at carrying value December 31, 2017 (In millions) Carrying Quoted Prices in Significant Significant Total Assets: Securities held to maturity, Fixed maturity securities: Government and agencies $ 21,331 $ 26,491 $ 0 $ 0 $ 26,491 Municipalities 357 0 462 0 462 Mortgage and asset-backed 26 0 8 19 27 Public utilities 3,300 0 3,698 0 3,698 Sovereign and 1,523 0 1,835 0 1,835 Banks/financial institutions 2,206 0 2,387 0 2,387 Other corporate 2,687 0 3,172 0 3,172 Other investments (1) 3,017 0 15 2,987 3,002 Total assets $ 34,447 $ 26,491 $ 11,577 $ 3,006 $ 41,074 Liabilities: Other policyholders’ funds $ 6,939 $ 0 $ 0 $ 6,841 $ 6,841 Notes payable 5,267 0 5,288 265 5,553 Total liabilities $ 12,206 $ 0 $ 5,288 $ 7,106 $ 12,394 (1) Excludes policy loans of $210 and equity method investments of $118 , at carrying value
Fair Value Assets Securities Carried At Fair Value Primary Pricing Sources	The following tables present the pricing sources for the fair values of the Company's fixed maturity and equity securities. June 30, 2018 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: (1) Government and agencies: Third party pricing vendor $ 33,591 $ 1,525 $ 0 $ 35,116 Total government and agencies 33,591 1,525 0 35,116 Municipalities: Third party pricing vendor 0 1,928 0 1,928 Total municipalities 0 1,928 0 1,928 Mortgage- and asset-backed securities: Third party pricing vendor 0 169 0 169 Broker/other 0 0 178 178 Total mortgage- and asset-backed securities 0 169 178 347 Public utilities: Third party pricing vendor 0 7,258 0 7,258 Broker/other 0 0 106 106 Total public utilities 0 7,258 106 7,364 Sovereign and supranational: Third party pricing vendor 0 1,743 0 1,743 Total sovereign and supranational 0 1,743 0 1,743 Banks/financial institutions: Third party pricing vendor 0 8,959 0 8,959 Broker/other 0 200 23 223 Total banks/financial institutions 0 9,159 23 9,182 Other corporate: Third party pricing vendor 0 30,005 0 30,005 Broker/other 0 0 196 196 Total other corporate 0 30,005 196 30,201 Total securities available for sale $ 33,591 $ 51,787 $ 503 $ 85,881 (1) Equity securities, carried at fair value: (1) Third party pricing vendor $ 961 $ 75 $ 0 $ 1,036 Broker/other 50 0 17 67 Total equity securities $ 1,011 $ 75 $ 17 $ 1,103 (1) (1) Includes perpetual securities December 31, 2017 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities available for sale, carried at fair value: Fixed maturity securities: (1) Government and agencies: Third party pricing vendor $ 30,109 $ 1,121 $ 0 $ 31,230 Total government and agencies 30,109 1,121 0 31,230 Municipalities: Third party pricing vendor 0 1,370 0 1,370 Total municipalities 0 1,370 0 1,370 Mortgage- and asset-backed securities: Third party pricing vendor 0 269 0 269 Broker/other 0 0 175 175 Total mortgage- and asset-backed securities 0 269 175 444 Public utilities: Third party pricing vendor 0 7,886 0 7,886 Broker/other 0 0 68 68 Total public utilities 0 7,886 68 7,954 Sovereign and supranational: Third party pricing vendor 0 1,807 0 1,807 Broker/other 0 102 0 102 Total sovereign and supranational 0 1,909 0 1,909 Banks/financial institutions: Third party pricing vendor 0 8,908 0 8,908 Broker/other 0 0 25 25 Total banks/financial institutions 0 8,908 25 8,933 Other corporate: Third party pricing vendor 0 32,327 0 32,327 Broker/other 0 0 146 146 Total other corporate 0 32,327 146 32,473 Total fixed maturity securities 30,109 53,790 414 84,313 Total securities available for sale $ 30,109 $ 53,790 $ 414 $ 84,313 (1) Equity securities, carried at fair value: Third party pricing vendor $ 1,001 $ 6 $ 0 $ 1,007 Broker/other 0 0 16 16 Total equity securities $ 1,001 $ 6 $ 16 $ 1,023 (1) Includes perpetual securities
Fair Value Assets Held-To-Maturity Securities Primary Pricing Sources	December 31, 2017 (In millions) Quoted Prices in Active Markets Significant Observable Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 26,491 $ 0 $ 0 $ 26,491 Total government and agencies 26,491 0 0 26,491 Municipalities: Third party pricing vendor 0 462 0 462 Total municipalities 0 462 0 462 Mortgage- and asset-backed securities: Third party pricing vendor 0 8 0 8 Broker/other 0 0 19 19 Total mortgage- and asset-backed securities 0 8 19 27 Public utilities: Third party pricing vendor 0 3,698 0 3,698 Total public utilities 0 3,698 0 3,698 Sovereign and supranational: Third party pricing vendor 0 1,835 0 1,835 Total sovereign and supranational 0 1,835 0 1,835 Banks/financial institutions: Third party pricing vendor 0 2,387 0 2,387 Total banks/financial institutions 0 2,387 0 2,387 Other corporate: Third party pricing vendor 0 3,172 0 3,172 Total other corporate 0 3,172 0 3,172 Total securities held to maturity $ 26,491 $ 11,562 $ 19 $ 38,072 June 30, 2018 (In millions) Quoted Prices in Active Markets for Identical Assets Significant Observable Inputs Significant Unobservable Inputs Total Securities held to maturity, carried at amortized cost: Fixed maturity securities: Government and agencies: Third party pricing vendor $ 27,209 $ 8 $ 0 $ 27,217 Total government and agencies 27,209 8 0 27,217 Municipalities: Third party pricing vendor 0 474 0 474 Total municipalities 0 474 0 474 Mortgage- and asset-backed securities: Broker/other 0 0 17 17 Total mortgage- and asset-backed securities 0 0 17 17 Public utilities: Third party pricing vendor 0 3,552 0 3,552 Total public utilities 0 3,552 0 3,552 Sovereign and supranational: Third party pricing vendor 0 1,843 0 1,843 Total sovereign and supranational 0 1,843 0 1,843 Banks/financial institutions: Third party pricing vendor 0 1,700 0 1,700 Total banks/financial institutions 0 1,700 0 1,700 Other corporate: Third party pricing vendor 0 3,153 0 3,153 Total other corporate 0 3,153 0 3,153 Total securities held to maturity $ 27,209 $ 10,730 $ 17 $ 37,956
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	Transfers between Hierarchy Levels and Level 3 Rollforward During the three- and six -month periods ended June 30, 2018 and 2017 , respectively, there were no transfers between Level 1 and 2 for assets and liabilities that are measured and carried at fair value on a recurring basis. The following tables present the changes in fair value of the Company's investments and derivatives carried at fair value classified as Level 3. Three Months Ended Fixed Maturities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 186 $ 83 $ 24 $ 143 $ 16 $ 154 $ 1 $ 607 Realized investment gains (losses) included in earnings 0 0 0 0 0 (42 ) (1 ) (43 ) Unrealized gains (losses) included in other comprehensive income (loss) (8 ) (1 ) (1 ) (1 ) 0 (2 ) 0 (13 ) Purchases, issuances, sales and settlements: Purchases 0 24 0 56 1 0 0 81 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements 0 0 0 (2 ) 0 0 0 (2 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 178 $ 106 $ 23 $ 196 $ 17 $ 110 $ 0 $ 630 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ (42 ) $ (1 ) $ (43 ) (1) Derivative assets and liabilities are presented net Three Months Ended Fixed Maturities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 195 $ 16 $ 24 $ 35 $ 4 $ 19 $ 2 $ 295 Realized investment gains (losses) included in 0 0 0 0 0 (10 ) 0 (10 ) Unrealized gains (losses) included in other 0 0 1 2 0 (2 ) 0 1 Purchases, issuances, sales and settlements: Purchases 0 37 0 40 10 0 0 87 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements (7 ) 0 0 0 0 0 0 (7 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 188 $ 53 $ 25 $ 77 $ 14 $ 7 $ 2 $ 366 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ (10 ) $ 0 $ (10 ) (1) Derivative assets and liabilities are presented net Six Months Ended Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 175 $ 68 $ 25 $ 146 $ 16 $ 22 $ 1 $ 453 Realized investment gains (losses) included 0 0 0 0 0 84 (1 ) 83 Unrealized gains (losses) included in other 3 (2 ) (2 ) (3 ) 0 4 0 0 Purchases, issuances, sales and settlements: Purchases 0 40 0 56 1 0 0 97 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 0 0 0 0 Settlements 0 0 0 (3 ) 0 0 0 (3 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 178 $ 106 $ 23 $ 196 $ 17 $ 110 $ 0 $ 630 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ 84 $ (1 ) $ 83 (1) Derivative assets and liabilities are presented net Six Months Ended Fixed Maturity Securities Equity Derivatives (1) (In millions) Mortgage- Public Banks/ Other Foreign Credit Total Balance, beginning of period $ 198 $ 16 $ 25 $ 0 $ 3 $ (21 ) $ 2 $ 223 Realized investment gains (losses) included in earnings 0 0 0 0 0 28 0 28 Unrealized gains (losses) included in other comprehensive income (loss) 6 0 0 2 0 0 0 8 Purchases, issuances, sales and settlements: Purchases 0 37 0 75 12 0 0 124 Issuances 0 0 0 0 0 0 0 0 Sales 0 0 0 0 (1 ) 0 0 (1 ) Settlements (16 ) 0 0 0 0 0 0 (16 ) Transfers into Level 3 0 0 0 0 0 0 0 0 Transfers out of Level 3 0 0 0 0 0 0 0 0 Balance, end of period $ 188 $ 53 $ 25 $ 77 $ 14 $ 7 $ 2 $ 366 Changes in unrealized gains (losses) relating $ 0 $ 0 $ 0 $ 0 $ 0 $ 28 $ 0 $ 28 (1) Derivative assets and liabilities are presented net
Fair Value Measurement Inputs and Valuation Techniques	The following tables summarize the significant unobservable inputs used in the valuation of the Company's Level 3 investments and derivatives carried at fair value. Included in the tables are the inputs or range of possible inputs that have an effect on the overall valuation of the financial instruments. June 30, 2018 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 178 Consensus pricing Offered quotes N/A (c) Public utilities 106 Discounted cash flow Credit spreads N/A (c) Banks/financial institutions 23 Consensus pricing Offered quotes N/A (c) Other corporate 196 Discounted cash flow Credit spreads N/A (c) Equity securities 17 Net asset value Offered quotes N/A (c) Other assets: Foreign currency swaps 145 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) CDS spreads 15 - 105 bps 57 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) Total assets $ 722 Liabilities: Other liabilities: Foreign currency swaps $ 88 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) CDS spreads 34 - 188 bps 4 Discounted cash flow Interest rates (USD) 2.92% (a) Interest rates (JPY) .25% - .75% (b) Total liabilities $ 92 (a) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (b) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps (c) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. December 31, 2017 (In millions) Fair Value Valuation Technique(s) Unobservable Input Range Assets: Securities available for sale, carried at fair value: Fixed maturity securities: Mortgage- and asset-backed securities $ 175 Consensus pricing Offered quotes N/A (c) Public utilities 68 Discounted cash flow Credit spreads N/A (c) Banks/financial institutions 25 Consensus pricing Offered quotes N/A (c) Other corporate 146 Discounted cash flow Credit spreads N/A (c) Equity securities 16 Net asset value Offered quotes N/A (c) Other assets: Foreign currency swaps 80 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) CDS spreads 9 - 90 bps 70 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) Credit default swaps 1 Discounted cash flow Base correlation 46.33% - 49.65% (d) CDS spreads 25 bps Recovery rate 37.24% Total assets $ 581 Liabilities: Other liabilities: Foreign currency swaps $ 120 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) CDS spreads 13 - 157 bps 8 Discounted cash flow Interest rates (USD) 2.40% - 2.54% (a) Interest rates (JPY) .26% - .85% (b) Total liabilities $ 128 (a) Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps (b) Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps (c) N/A represents securities where the Company receives unadjusted broker quotes and for which there is no transparency into the providers' valuation techniques or unobservable inputs. (d) Range of base correlation for the Company's bespoke tranche for attachment and detachment points corresponding to market indices

POLICY LIABILITIES (Tables)

POLICY LIABILITIES (Tables)	6 Months Ended
	Jun. 30, 2018
Insurance Loss Reserves [Abstract]
Schedule of Liability for Unpaid Claims Adjustment Expense	Changes in the liability for unpaid policy claims were as follows: Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Unpaid supplemental health claims, beginning of period $ 4,041 $ 3,854 $ 3,881 $ 3,707 Less reinsurance recoverables 31 30 28 27 Net balance, beginning of period 4,010 3,824 3,853 3,680 Add claims incurred during the period related to: Current year 1,779 1,772 3,621 3,520 Prior years (133 ) (138 ) (325 ) (260 ) Total incurred 1,646 1,634 3,296 3,260 Less claims paid during the period on claims incurred during: Current year 1,226 1,220 1,746 1,721 Prior years 426 400 1,540 1,461 Total paid 1,652 1,620 3,286 3,182 Effect of foreign exchange rate changes on unpaid claims (91 ) 4 50 84 Net balance, end of period 3,913 3,842 3,913 3,842 Add reinsurance recoverables 29 30 29 30 Unpaid supplemental health claims, end of period 3,942 3,872 3,942 3,872 Unpaid life claims, end of period 582 409 582 409 Total liability for unpaid policy claims $ 4,524 $ 4,281 $ 4,524 $ 4,281

REINSURANCE (Tables)

REINSURANCE (Tables)	6 Months Ended
	Jun. 30, 2018
Reinsurance Disclosures [Abstract]
Effects of Reinsurance	The following table reconciles direct premium income and direct benefits and claims to net amounts after the effect of reinsurance. Three Months Ended Six Months Ended (In millions) 2018 2017 2018 2017 Direct premium income $ 4,793 $ 4,752 $ 9,626 $ 9,476 Ceded to other companies: Ceded Aflac Japan closed blocks (126 ) (130 ) (256 ) (260 ) Other (16 ) (13 ) (30 ) (25 ) Assumed from other companies: Retrocession activities 53 55 107 109 Other 2 1 3 3 Net premium income $ 4,706 $ 4,665 $ 9,450 $ 9,303 Direct benefits and claims $ 3,106 $ 3,117 $ 6,225 $ 6,246 Ceded benefits and change in reserves for future benefits: Ceded Aflac Japan closed blocks (114 ) (119 ) (231 ) (241 ) Eliminations 11 13 23 26 Other (12 ) (11 ) (23 ) (22 ) Assumed from other companies: Retrocession activities 49 52 101 106 Eliminations (11 ) (13 ) (23 ) (26 ) Other 2 0 1 2 Benefits and claims, net $ 3,031 $ 3,039 $ 6,073 $ 6,091

NOTES PAYABLE (Tables)

NOTES PAYABLE (Tables)	6 Months Ended
	Jun. 30, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	A summary of notes payable follows: (In millions) June 30, 2018 December 31, 2017 2.40% senior notes due March 2020 $ 549 $ 548 4.00% senior notes due February 2022 348 348 3.625% senior notes due June 2023 697 697 3.625% senior notes due November 2024 746 745 3.25% senior notes due March 2025 446 446 2.875% senior notes due October 2026 297 297 6.90% senior notes due December 2039 220 220 6.45% senior notes due August 2040 254 254 4.00% senior notes due October 2046 394 394 Yen-denominated senior notes and subordinated debentures: .932% senior notes due January 2027 (principal amount 60.0 billion yen) 540 528 2.108% subordinated debentures due October 2047 (principal amount 60.0 billion yen) 538 526 Yen-denominated loans: Variable interest rate loan due September 2021 (.32% in 2018 and 2017, principal amount 5.0 billion yen) 45 44 Variable interest rate loan due September 2023 (.47% in 2018 and 2017, principal amount 25.0 billion yen) 225 220 Capitalized lease obligations payable through 2025 16 22 Total notes payable $ 5,315 $ 5,289 Amounts in the table above are reported net of debt issuance costs and issuance premiums or discounts, if applicable, that are being amortized over the life of the notes.
Schedule of Line of Credit Facilities	A summary of the Company's lines of credit as of June 30, 2018 follows: Borrower Type Term Expiration Date Capacity Amount Outstanding Interest Rate on Borrowed Amount Maturity Period Commitment Fee Business Purpose Aflac Incorporated uncommitted bilateral 364 days November 30, 2018 $100 million $0 million The rate quoted by the bank and agreed upon at the time of borrowing Up to 3 months None General corporate purposes Aflac Incorporated unsecured revolving 3 years March 31, 2019, or the date commitments are terminated pursuant to an event of default 100.0 billion yen 0.0 billion yen A rate per annum equal to (a) Tokyo interbank market rate (TIBOR) plus, the alternative applicable TIBOR margin during the availability period from the closing date to the commitment termination date or (b) the TIBOR rate offered by the agent to major banks in yen for the applicable period plus, the applicable alternative TIBOR margin during the term out period No later than .30% to .50%, depending on the Parent Company's debt ratings as of the date of determination General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated unsecured revolving 5 years April 4, 2023, or the date commitments are terminated pursuant to an event of default (1) 55.0 billion yen, or the equivalent amount in U.S. dollars 0.0 billion yen A rate per annum equal to, at the Company's option, either, (a) London Interbank Offered Rate (LIBOR) adjusted for certain costs or (b) a base rate determined by reference to the highest of (1) the federal funds rate plus 1/2 of 1%, (2) the rate of interest for such day announced by Mizuho Bank, Ltd. as its prime rate, or (3) the eurocurrency rate for an interest period of one month plus 1.00%, in each case plus an applicable margin No later than April 4, 2023 .085% to .225%, depending on the Parent Company's debt ratings as of the date of determination General corporate purposes, including a capital contingency plan for the operations of the Parent Company Aflac Incorporated uncommitted bilateral None specified None specified $50 million $0 million A rate per annum equal to, at the Parent Company's option, either (a) a eurocurrency rate determined by reference to the agent's LIBOR for the interest period relevant to such borrowing or (b) the base rate determined by reference to the greater of (i) the prime rate as determined by the agent, and (ii) the sum of 0.50% and the federal funds rate for such day Up to 3 months None General corporate purposes Aflac (2) uncommitted revolving 364 days November 30, 2018 $250 million $0 million USD three-month LIBOR plus 75 basis points per annum 3 months None General corporate purposes Aflac Incorporated (2) uncommitted revolving 364 days April 2, 2019 37.5 billion yen 0.0 billion yen Three-month TIBOR plus 80 basis points per annum 3 months None General corporate purposes (1) Effective April 4, 2018, the prior expiration date of September 18, 2020 was extended to April 4, 2023. (2) Intercompany credit agreement

SHAREHOLDERS' EQUITY (Tables)

SHAREHOLDERS' EQUITY (Tables)	6 Months Ended
	Jun. 30, 2018
Stockholders' Equity Note [Abstract]
Schedule of Common Stock Outstanding Roll Forward	The following table is a reconciliation of the number of shares of the Company's common stock for the six -month periods ended June 30 . (In thousands of shares) 2018 2017 Common stock - issued: Balance, beginning of period 1,345,762 1,342,498 Exercise of stock options and issuance of restricted shares 1,299 1,576 Balance, end of period 1,347,061 1,344,074 Treasury stock: Balance, beginning of period 564,852 530,877 Purchases of treasury stock: Open market 13,441 22,310 Other 328 346 Dispositions of treasury stock: Shares issued to AFL Stock Plan (400 ) (998 ) Exercise of stock options (327 ) (414 ) Other (105 ) (44 ) Balance, end of period 577,789 552,077 Shares outstanding, end of period 769,272 791,997
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table presents the approximate number of share-based awards to purchase shares, on a weighted-average basis, that were considered to be anti-dilutive and were excluded from the calculation of diluted earnings per share for the following periods. Three Months Ended Six Months Ended (In thousands) 2018 2017 2018 2017 Anti-dilutive share-based awards 48 838 28 740
Schedule of Accumulated Other Comprehensive Income (Loss)	Reclassifications from Accumulated Other Comprehensive Income The tables below are reconciliations of accumulated other comprehensive income by component for the following periods. Changes in Accumulated Other Comprehensive Income Three Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Total Balance, beginning of period $ (1,303 ) $ 5,206 $ (21 ) $ (197 ) $ 3,685 Other comprehensive (1) (463 ) (391 ) (2 ) (1 ) (857 ) Amounts reclassified from 0 21 0 3 24 Net current-period other (463 ) (370 ) (2 ) 2 (833 ) Balance, end of period $ (1,766 ) $ 4,836 $ (23 ) $ (195 ) $ 2,852 All amounts in the table above are net of tax. Three Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,650 ) $ 4,474 $ (22 ) $ (170 ) $ 2,632 Other comprehensive 70 698 (1 ) (2 ) 765 Amounts reclassified from 0 1 0 3 4 Net current-period other 70 699 (1 ) 1 769 Balance, end of period $ (1,580 ) $ 5,173 $ (23 ) $ (169 ) $ 3,401 All amounts in the table above are net of tax. Six Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Total Balance, beginning of period $ (1,750 ) $ 5,964 $ (23 ) $ (163 ) $ 4,028 Cumulative effect of change 0 (148 ) 0 0 (148 ) Cumulative effect of change (325 ) 734 (3 ) (32 ) 374 Other comprehensive (1) 309 (1,733 ) 3 (5 ) (1,426 ) Amounts reclassified from 0 19 0 5 24 Net current-period other 309 (1,714 ) 3 0 (1,402 ) Balance, end of period $ (1,766 ) $ 4,836 $ (23 ) $ (195 ) $ 2,852 All amounts in the table above are net of tax. (1) Amounts have been corrected to exclude the cumulative effects of changes in accounting principles for financial instruments and the tax effects from tax reform as identified in the rollforward of Accumulated Other Comprehensive Income within the Consolidated Statements of Shareholder’s Equity. Six Months Ended (In millions) Unrealized Foreign Unrealized Unrealized Pension Liability Adjustment Total Balance, beginning of period $ (1,983 ) $ 4,805 $ (24 ) $ (168 ) $ 2,630 Other comprehensive 403 357 1 (6 ) 755 Amounts reclassified from 0 11 0 5 16 Net current-period other 403 368 1 (1 ) 771 Balance, end of period $ (1,580 ) $ 5,173 $ (23 ) $ (169 ) $ 3,401 All amounts in the table above are net of tax.
Reclassification Out Of Accumulated Other Comprehensive Income	The tables below summarize the amounts reclassified from each component of accumulated other comprehensive income into net earnings for the following periods. Reclassifications Out of Accumulated Other Comprehensive Income (In millions) Three Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (2 ) Other-than-temporary impairment (26 ) Other gains (losses) (28 ) Total before tax 7 Tax (expense) or benefit (1) $ (21 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (4 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 1 Tax (expense) or benefit (1) $ (3 ) Net of tax Total reclassifications for the period $ (24 ) Net of tax (1) Based on 26% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details). (In millions) Three Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (6 ) Other-than-temporary impairment 5 Other gains (losses) (1 ) Total before tax 0 Tax (expense) or benefit (1) $ (1 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (5 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 2 Tax (expense) or benefit (1) $ (3 ) Net of tax Total reclassifications for the period $ (4 ) Net of tax (1) Based on 35% tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details) (In millions) Six Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (2 ) Other-than-temporary impairment (24 ) Other gains (losses) (26 ) Total before tax 7 Tax (expense) or benefit (1) $ (19 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (8 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 3 Tax (expense) or benefit (1) $ (5 ) Net of tax Total reclassifications for the period $ (24 ) Net of tax (1) Based on 27% blended tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details). (In millions) Six Months Ended Details about Accumulated Other Comprehensive Income Components Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Unrealized gains (losses) on available-for-sale $ (16 ) Other-than-temporary impairment (1 ) Other gains (losses) (17 ) Total before tax 6 Tax (expense) or benefit (1) $ (11 ) Net of tax Amortization of defined benefit pension items: Actuarial gains (losses) $ (8 ) Acquisition and operating expenses (2) Prior service (cost) credit 0 Acquisition and operating expenses (2) 3 Tax (expense) or benefit (1) $ (5 ) Net of tax Total reclassifications for the period $ (16 ) Net of tax (1) Based on 35% tax rate (2) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details)

SHARE-BASED COMPENSATION (Table

SHARE-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Options Outstanding and Exercisable	The following table provides information on stock options outstanding and exercisable at June 30, 2018 . Stock Weighted-Average Aggregate Weighted-Average Outstanding 6,057 5.4 $ 89 $ 28.26 Exercisable 4,365 4.4 71 26.77
Schedule of Nonvested Restricted Stock Units Activity	The following table summarizes restricted stock activity during the six -month period ended June 30 . (In thousands of shares) Shares Weighted-Average Grant-Date Fair Value Per Share Restricted stock at December 31, 2017 3,635 $ 32.40 Granted in 2018 993 44.10 Canceled in 2018 (69 ) 33.38 Vested in 2018 (1,062 ) 31.69 Restricted stock at June 30, 2018 3,497 $ 35.91

BENEFIT PLANS (Tables)

BENEFIT PLANS (Tables)	6 Months Ended
	Jun. 30, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Schedule of Net Benefit Costs	Pension and other postretirement benefit expenses are included in acquisition and operating expenses in the consolidated statement of earnings, which includes other components of net periodic pension cost and postretirement costs (other than service costs) of $7 million and $10 million for the three-month periods and $13 million and $15 million for the six-month periods ended June 30, 2018 and 2017 , respectively. Total net periodic cost includes the following components: Three Months Ended June 30, Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2018 2017 2018 2017 2018 2017 Components of net periodic Service cost $ 5 $ 4 $ 7 $ 6 $ 0 $ 0 Interest cost 1 2 8 8 1 1 Expected return on plan (1 ) (1 ) (6 ) (5 ) 0 0 Amortization of net actuarial 0 1 4 4 0 0 Amortization of prior service 0 0 0 0 0 0 Net periodic (benefit) cost $ 5 $ 6 $ 13 $ 13 $ 1 $ 1 Six Months Ended June 30, Pension Benefits Other Japan U.S. Postretirement Benefits (In millions) 2018 2017 2018 2017 2018 2017 Components of net periodic Service cost $ 10 $ 9 $ 14 $ 12 $ 0 $ 0 Interest cost 3 3 17 16 1 1 Expected return on plan (3 ) (2 ) (13 ) (11 ) 0 0 Amortization of net actuarial 0 1 8 7 0 0 Amortization of prior service 0 0 0 0 0 0 Net periodic (benefit) cost $ 10 $ 11 $ 26 $ 24 $ 1 $ 1

Summary of Significant Accoun32

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions		Feb. 13, 2018	Jun. 30, 2018	Jun. 30, 2017USD ($)		Jan. 01, 2018USD ($)	Dec. 31, 2017USD ($)
Significant Accounting Policies [Line Items]
Stock Split, Conversion Ratio		2
Common stock as a percentage of two-for-one stock split dividend		100.00%
Aflac Japan
Significant Accounting Policies [Line Items]
Percentage of the Company's total assets			85.00%				83.00%
Percentage of the Company's total revenues			70.00%	69.00%
Upper Limit | Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Estimation of Percent of Leases Within Scope of the Guidance to Total Assets			1.00%
Accumulated other comprehensive income (loss): | Accounting Standards Update 2016-01
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes	[1]			$ 0		$ (148)
Accumulated other comprehensive income (loss): | Accounting Standards Update 2018-02
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes	[1]			0		374
Retained earnings | Accounting Standards Update 2016-01
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes				0	[1]	148	$ 148	[1]
Retained earnings | Accounting Standards Update 2018-02
Significant Accounting Policies [Line Items]
Cumulative effect of change in accounting principle, net of income taxes				$ 0	[1]	$ (374)	$ (374)	[1]
[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018.

BUSINESS SEGMENT INFORMATION -

BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)segment	Jun. 30, 2017USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of Reportable Insurance Business Segments | segment				2
Net earned premiums		$ 4,706	$ 4,665	$ 9,450	$ 9,303
Net investment income		862	802	1,699	1,596
Total adjusted revenues		5,539	5,429	11,084	10,828
Realized investment gains (losses)	[1],[2]	50	(1)	(30)	(91)
Total revenues		5,589	5,428	11,054	10,737
Gain (loss) on change in fair value of derivative, corporate		7		9
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		3,227	3,222	6,490	6,416
Net investment income, less amortized hedge costs	[2]	606	557	1,194	1,115
Other income (loss)		11	10	22	20
Total revenues		3,844	3,789	7,706	7,551
Hedge costs		55	56	110	108
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,426	1,388	2,853	2,778
Net investment income		182	180	357	358
Other income (loss)		2	2	4	3
Total revenues		1,610	1,570	3,214	3,139
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Total revenues	[1]	$ 85	$ 70	$ 164	$ 138
[1]	Amortized hedge costs in Aflac Japan were partially offset by derivatives entered into as part of corporate activities and resulted in a benefit of $7 for the three-month period and $9 for the six-month period ended June 30, 2018, respectively, which has been reclassified from realized investment gains (losses) and reported as an increase in net investment income when analyzing operations.
[2]	Amortized hedge costs related to hedging U.S. dollar-denominated investments held in Aflac Japan were $55 and $56 for the three- month periods and $110 and $108 for the six-month periods ended June 30, 2018, and 2017, respectively, and have been reclassified from realized investment gains (losses) and reported as a deduction from net investment income when analyzing segment operations.

BUSINESS SEGMENT INFORMATION 34

BUSINESS SEGMENT INFORMATION - Operations by Segment - Pretax Earnings (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings		$ 1,138	$ 1,073	$ 2,247	$ 2,100
Realized investment gains (losses)	[1],[2],[3]	35	(19)	(63)	(128)
Other income (loss)		(42)	(9)	(70)	(28)
Earnings before income taxes		1,131	1,045	2,114	1,944
Income taxes applicable to pretax adjusted earnings		303	342	592	694
Effect of foreign currency translation on after tax adjusted earnings		7	(9)	29	(3)
Gain (loss) on change in fair value of derivative, corporate		7		9
Gain (loss) on change in fair value of derivative, interest rate component		17	20	33	41
Aflac Japan
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[2]	836	791	1,654	1,560
Hedge costs		55	56	110	108
Aflac U.S.
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings		340	330	677	640
Corporate and other
Segment Reporting, Reconciling Item for Adjusted Profit (Loss) from Segment to Consolidated [Line Items]
Pretax adjusted earnings	[1]	$ (38)	$ (48)	$ (84)	$ (100)
[1]	Amortized hedge costs in Aflac Japan were partially offset by derivatives entered into as part of corporate activities and resulted in a benefit of $7 for the three-month period and $9 for the six-month period ended June 30, 2018 which has been reclassified from realized investment gains (losses) and reported as an increase in pretax adjusted earnings when analyzing operations.
[2]	Amortized hedge costs related to hedging U.S. dollar-denominated investments held in Aflac Japan were $55 and $56 for the three- month periods and $110 and $108 for the six-month periods ended June 30, 2018, and 2017, respectively, and have been reclassified from realized investment gains (losses) and reported as a deduction from pretax adjusted earnings when analyzing segment operations.
[3]	Excluding a gain of $17 and $20 for the three-month periods and $33 and $41 for the six-month periods ended June 30, 2018, and 2017, respectively, related to the interest rate component of the change in fair value of foreign currency swaps on notes payable which is included in adjusted earnings when analyzing segment operations

BUSINESS SEGMENT INFORMATION 35

BUSINESS SEGMENT INFORMATION - Operations by Segment - Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 141,986	$ 137,217
Aflac Japan
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	120,228	114,402
Aflac U.S.
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	19,588	19,893
Corporate and other
Segment Reporting, Asset Reconciling Item [Line Items]
Assets	$ 2,170	$ 2,922

INVESTMENTS - Available-for-sal

INVESTMENTS - Available-for-sale Debt Securities (Details) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		$ 78,935	[1],[2]	$ 75,132	[3]
Gross Unrealized Gains		8,386		9,985
Gross Unrealized Losses		1,440		804
Fair Value	[4]	85,881	[1],[2]	84,313	[3]
Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fair Value	[4]	85,881		84,313
Perpetual securities, amortized cost		1,446		1,462
Perpetual securities, fair value		1,612		1,789
Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		44,538		40,378
Gross Unrealized Gains		5,636		5,582
Gross Unrealized Losses		324		350
Fair Value		49,850		45,610
Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		34,397		34,754
Gross Unrealized Gains		2,750		4,403
Gross Unrealized Losses		1,116		454
Fair Value		36,031		38,703
Japan government and agencies | Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		31,384		27,980
Gross Unrealized Gains		3,742		3,363
Gross Unrealized Losses		150		271
Fair Value		34,976		31,072
Municipalities | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fair Value		1,928		1,370
Municipalities | Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		375		314
Gross Unrealized Gains		32		28
Gross Unrealized Losses		9		12
Fair Value		398		330
Municipalities | Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		1,396		872
Gross Unrealized Gains		135		168
Gross Unrealized Losses		1		0
Fair Value		1,530		1,040
Mortgage- and asset-backed securities | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fair Value		347		444
Mortgage- and asset-backed securities | Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		156		242
Gross Unrealized Gains		22		29
Gross Unrealized Losses		0		0
Fair Value		178		271
Mortgage- and asset-backed securities | Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		162		161
Gross Unrealized Gains		8		12
Gross Unrealized Losses		1		0
Fair Value		169		173
Public utilities | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fair Value		7,364		7,954
Public utilities | Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		1,663		1,635
Gross Unrealized Gains		313		352
Gross Unrealized Losses		3		6
Fair Value		1,973		1,981
Public utilities | Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		4,939		5,116
Gross Unrealized Gains		555		884
Gross Unrealized Losses		103		27
Fair Value		5,391		5,973
Sovereign and supranational | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fair Value		1,743		1,909
Sovereign and supranational | Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		1,263		1,380
Gross Unrealized Gains		188		190
Gross Unrealized Losses		30		1
Fair Value		1,421		1,569
Sovereign and supranational | Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		264		267
Gross Unrealized Gains		58		73
Gross Unrealized Losses		0		0
Fair Value		322		340
Banks/financial institutions | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fair Value		9,182		8,933
Banks/financial institutions | Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		5,399		4,742
Gross Unrealized Gains		651		811
Gross Unrealized Losses		126		53
Fair Value		5,924		5,500
Banks/financial institutions | Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		2,871		2,808
Gross Unrealized Gains		417		633
Gross Unrealized Losses		30		8
Fair Value		3,258		3,433
Other corporate | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Fair Value		30,201		32,473
Other corporate | Yen-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		4,298		4,085
Gross Unrealized Gains		688		809
Gross Unrealized Losses		6		7
Fair Value		4,980		4,887
Other corporate | Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		24,632		25,384
Gross Unrealized Gains		1,569		2,620
Gross Unrealized Losses		980		418
Fair Value		25,221		27,586
U.S. government and agencies | Dollar-denominated | Fixed maturities
Debt Securities, Available-for-sale [Line Items]
Cost or Amortized Cost		133		146
Gross Unrealized Gains		8		13
Gross Unrealized Losses		1		1
Fair Value		$ 140		$ 158
[1]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[2]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[3]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[4]	Includes perpetual securities

INVESTMENTS - Held-to-Maturity

INVESTMENTS - Held-to-Maturity Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	$ 31,259	$ 31,430
Gross Unrealized Gains	6,708	6,651
Gross Unrealized Losses	11	9
Fair Value	37,956	38,072
Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	37,956	38,072
Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	31,259	31,430
Gross Unrealized Gains	6,708	6,651
Gross Unrealized Losses	11	9
Fair Value	37,956	38,072
Japan government and agencies | Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	21,808	21,331
Gross Unrealized Gains	5,409	5,160
Gross Unrealized Losses	0	0
Fair Value	27,217	26,491
Municipalities | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	363	357
Fair Value	474	462
Municipalities | Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	363	357
Gross Unrealized Gains	111	105
Gross Unrealized Losses	0	0
Fair Value	474	462
Mortgage- and asset-backed securities | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	16	26
Fair Value	17	27
Mortgage- and asset-backed securities | Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	16	26
Gross Unrealized Gains	1	1
Gross Unrealized Losses	0	0
Fair Value	17	27
Public utilities | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,236	3,300
Fair Value	3,552	3,698
Public utilities | Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	3,236	3,300
Gross Unrealized Gains	317	398
Gross Unrealized Losses	1	0
Fair Value	3,552	3,698
Sovereign and supranational | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	1,557	1,523
Fair Value	1,843	1,835
Sovereign and supranational | Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	1,557	1,523
Gross Unrealized Gains	286	312
Gross Unrealized Losses	0	0
Fair Value	1,843	1,835
Banks/financial institutions | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	1,532	2,206
Fair Value	1,700	2,387
Banks/financial institutions | Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	1,532	2,206
Gross Unrealized Gains	178	190
Gross Unrealized Losses	10	9
Fair Value	1,700	2,387
Other corporate | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	2,747	2,687
Fair Value	3,153	3,172
Other corporate | Yen-denominated | Fixed maturities
Schedule of Held-to-maturity Securities [Line Items]
Securities held to maturity, fixed maturities, amortized cost	2,747	2,687
Gross Unrealized Gains	406	485
Gross Unrealized Losses	0	0
Fair Value	$ 3,153	$ 3,172

INVESTMENTS - Equity Securities

INVESTMENTS - Equity Securities (Details) $ in Millions	Jun. 30, 2018USD ($)
Equity Securities, FV-NI [Line Items]
Fair Value	$ 1,103	[1],[2]
Yen-denominated
Equity Securities, FV-NI [Line Items]
Fair Value	712
Dollar-denominated
Equity Securities, FV-NI [Line Items]
Fair Value	391
Equity securities
Equity Securities, FV-NI [Line Items]
Perpetual securities, fair value	$ 69
[1]	Includes perpetual securities
[2]	Includes perpetual securities ($69 at fair value)

INVESTMENTS - Equity Securiti39

INVESTMENTS - Equity Securities, Prior Period (Details) $ in Millions	Dec. 31, 2017USD ($)
Investment [Line Items]
Equity securities, available-for-sale	$ 1,023
Yen-denominated
Investment [Line Items]
Equity securities, available-for-sale	695
Dollar-denominated
Investment [Line Items]
Equity securities, available-for-sale	$ 328

INVESTMENTS - Additional Inform

INVESTMENTS - Additional Information (Detail) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2018USD ($)investment	Mar. 31, 2018investment	Jun. 30, 2017USD ($)investment	Mar. 31, 2017investment	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Schedule of Investments [Line Items]
Held to maturity securities transferred to available for sale securities, number of investments | investment	0	0	3	0
Debt Securities, Held-to-maturity, Transfer, Amount			$ 773
Debt Securities, Held-to-maturity, Transfer, Unrealized Gain (Loss)			$ 47
Equity securities, FV-NI, unrealized gain (loss)	$ 19				$ (24)
Allowance for loan loss	21				21	$ 11
Transitional real estate loan commitments	1,200				1,200
Commercial mortgage loan commitments	79				79
Middle market loan program unfunded amount	90				90	$ 109
Middle market loan commitments	774				774
Limited partnerships investment commitments	$ 1,100				$ 1,100
Percentage that the lending policy requires that the fair value of the securities and/or unrestricted cash received as collateral be of the fair value of the loaned securities	102.00%				102.00%

INVESTMENTS - Contractual and E

INVESTMENTS - Contractual and Economic Maturities of Investments in Fixed Maturities (Detail) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Available for sale:
Due in one year or less	[1]	$ 348
Due after one year through five years	[1]	3,910
Due after five years through 10 years	[1]	11,813
Due after 10 years	[1]	62,547
Mortgage- and asset-backed securities	[1]	317
Total fixed maturity securities, available for sale, amortized cost		78,935	[1],[2]	$ 75,132	[3]
Held to maturity:
Due in one year or less		498
Due after one year through five years		353
Due after five years through 10 years		1,585
Due after 10 years		28,807
Mortgage- and asset-backed securities		16
Total fixed maturity securities, held to maturity, amortized cost		31,259		31,430
Available for sale:
Due in one year or less	[1]	359
Due after one year through five years	[1]	4,070
Due after five years through 10 years	[1]	11,912
Due after 10 years	[1]	69,193
Mortgage- and asset-backed securities	[1]	347
Total fixed maturity securities, available for sale, fair value	[4]	85,881	[1],[2]	84,313	[3]
Held to maturity:
Due in one year or less		505
Due after one year through five years		366
Due after five years through 10 years		1,715
Due after 10 years		35,353
Mortgage- and asset-backed securities		17
Total fixed maturity securities, held to maturity, fair value		$ 37,956		$ 38,072
[1]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[2]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[3]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[4]	Includes perpetual securities

INVESTMENTS - Investment Exposu

INVESTMENTS - Investment Exposures Individually Exceeded 10% of Shareholders' Equity (Details) - Japan National Government - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Summary of Investment Holdings [Line Items]
Credit Rating	[1]	A+	A
Amortized Cost	[1]	$ 51,881	$ 48,399
Fair Value	[1]	$ 60,734	$ 56,532
[1]	Japan Government Bonds (JGBs) or JGB-backed securities

INVESTMENTS - Information Regar

INVESTMENTS - Information Regarding Pretax Realized Gains and Losses From Investments (Detail) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017		Jun. 30, 2018	Jun. 30, 2017
Gain (Loss) on Securities [Line Items]
Other-than-temporary impairment losses realized		$ (5)			$ (12)
Loan loss reserves		(3)	$ (2)		(10)	$ (3)
Derivative gains (losses)		(172)	(51)		(28)	(103)
Foreign currency gains (losses)		192	(1)		(36)	(73)
Total realized investment gains (losses)		3	(56)		(131)	(196)
Other-than-temporary impairment losses			(9)			(19)
Derivatives and other
Gain (Loss) on Securities [Line Items]
Total realized investment gains (losses)		20	(52)		(64)	(176)
Equity securities
Gain (Loss) on Securities [Line Items]
Total realized investment gains (losses)	[1],[2]	18	15	[3]	(28)	34	[3]
Other-than-temporary impairment losses			(6)			(12)
Available-for-sale securities | Fixed maturities
Gain (Loss) on Securities [Line Items]
Gross gains from sales	[1]	12	10		22	22
Gross losses from sales	[1]	(71)	(8)		(73)	(19)
Foreign exchange gains (losses)	[1]	29	(18)		24	(50)
Other-than-temporary impairment losses realized	[1]	(2)	(1)		(2)	(4)
Total realized investment gains (losses)	[1]	$ (32)	$ (17)		$ (29)	$ (51)
[1]	Includes perpetual securities
[2]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments.
[3]	Includes impairments of $6 for the three-month period and $12 for the six-month period ended June 30, 2017

INVESTMENTS - Net Effect on Sha

INVESTMENTS - Net Effect on Shareholders' Equity of Unrealized Gains and Losses from Investment Securities (Detail) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Investments [Abstract]
Unrealized Gains (Losses) on Available-for-sale Securities	[1]	$ 6,946	$ 9,358
Deferred income taxes	[1]	(2,110)	(3,394)
Shareholders' equity, unrealized gains (losses) on investment securities	[1],[2]	$ 4,836	$ 5,964
[1]	See Note 1 for discussion of the accounting treatment of tax on amounts recorded in accumulated other comprehensive income pursuant to the Tax Act and for the adoption of accounting guidance on January 1, 2018 related to financial instruments.
[2]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments.

INVESTMENTS - Fair Value and Gr

INVESTMENTS - Fair Value and Gross Unrealized Losses for Securities That Have Been in Continuous Unrealized Loss Position (Detail) - Fixed maturities - USD ($) $ in Millions		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	$ 22,933	$ 16,685
Total Unrealized Losses	[1]	1,451	813
Less than 12 months Fair Value	[1]	12,822	5,776
Less than 12 months Unrealized Losses	[1]	522	77
12 months or longer Fair Value	[1]	10,111	10,909
12 months or longer Unrealized Losses	[1]	929	736
Dollar-denominated | U.S. government and agencies
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	78	74
Total Unrealized Losses	[1]	1	1
Less than 12 months Fair Value	[1]	74	74
Less than 12 months Unrealized Losses	[1]	1	1
12 months or longer Fair Value	[1]	4	0
12 months or longer Unrealized Losses	[1]	0	0
Dollar-denominated | Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	261
Total Unrealized Losses	[1]	1
Less than 12 months Fair Value	[1]	261
Less than 12 months Unrealized Losses	[1]	1
12 months or longer Fair Value	[1]	0
12 months or longer Unrealized Losses	[1]	0
Dollar-denominated | Mortgage- and asset-backed securities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	86
Total Unrealized Losses	[1]	1
Less than 12 months Fair Value	[1]	71
Less than 12 months Unrealized Losses	[1]	1
12 months or longer Fair Value	[1]	15
12 months or longer Unrealized Losses	[1]	0
Dollar-denominated | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	1,664	785
Total Unrealized Losses	[1]	103	27
Less than 12 months Fair Value	[1]	1,200	221
Less than 12 months Unrealized Losses	[1]	52	3
12 months or longer Fair Value	[1]	464	564
12 months or longer Unrealized Losses	[1]	51	24
Dollar-denominated | Sovereign and supranational
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	13
Total Unrealized Losses	[1]	0
Less than 12 months Fair Value	[1]	13
Less than 12 months Unrealized Losses	[1]	0
12 months or longer Fair Value	[1]	0
12 months or longer Unrealized Losses	[1]	0
Dollar-denominated | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	696	362
Total Unrealized Losses	[1]	30	8
Less than 12 months Fair Value	[1]	561	316
Less than 12 months Unrealized Losses	[1]	20	5
12 months or longer Fair Value	[1]	135	46
12 months or longer Unrealized Losses	[1]	10	3
Dollar-denominated | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	13,044	7,741
Total Unrealized Losses	[1]	980	418
Less than 12 months Fair Value	[1]	8,391	2,839
Less than 12 months Unrealized Losses	[1]	362	50
12 months or longer Fair Value	[1]	4,653	4,902
12 months or longer Unrealized Losses	[1]	618	368
Yen-denominated | Japan government and agencies
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	3,647	5,255
Total Unrealized Losses	[1]	150	271
Less than 12 months Fair Value	[1]	0	1,264
Less than 12 months Unrealized Losses	[1]	0	9
12 months or longer Fair Value	[1]	3,647	3,991
12 months or longer Unrealized Losses	[1]	150	262
Yen-denominated | Municipalities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	137	129
Total Unrealized Losses	[1]	9	12
Less than 12 months Fair Value	[1]	13	10
Less than 12 months Unrealized Losses	[1]	0	0
12 months or longer Fair Value	[1]	124	119
12 months or longer Unrealized Losses	[1]	9	12
Yen-denominated | Public utilities
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	268	83
Total Unrealized Losses	[1]	4	6
Less than 12 months Fair Value	[1]	180	0
Less than 12 months Unrealized Losses	[1]	1	0
12 months or longer Fair Value	[1]	88	83
12 months or longer Unrealized Losses	[1]	3	6
Yen-denominated | Sovereign and supranational
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	286	309
Total Unrealized Losses	[1]	30	1
Less than 12 months Fair Value	[1]	286	309
Less than 12 months Unrealized Losses	[1]	30	1
12 months or longer Fair Value	[1]	0	0
12 months or longer Unrealized Losses	[1]	0	0
Yen-denominated | Banks/financial institutions
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	2,344	1,507
Total Unrealized Losses	[1]	136	62
Less than 12 months Fair Value	[1]	1,478	394
Less than 12 months Unrealized Losses	[1]	50	4
12 months or longer Fair Value	[1]	866	1,113
12 months or longer Unrealized Losses	[1]	86	58
Yen-denominated | Other corporate
Investments, Unrealized Loss Position [Line Items]
Total Fair Value	[1]	409	440
Total Unrealized Losses	[1]	6	7
Less than 12 months Fair Value	[1]	294	349
Less than 12 months Unrealized Losses	[1]	4	4
12 months or longer Fair Value	[1]	115	91
12 months or longer Unrealized Losses	[1]	$ 2	$ 3
[1]	Includes perpetual securities

INVESTMENTS - Other Investments

INVESTMENTS - Other Investments (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Other investments	[1]	$ 5,831	$ 3,402
Transitional real estate loans
Investment Holdings [Line Items]
Other investments		3,247	1,235
Commercial mortgage loans
Investment Holdings [Line Items]
Other investments		966	908
Middle market loans
Investment Holdings [Line Items]
Other investments		1,097	859
Policy loans
Investment Holdings [Line Items]
Other investments		222	210
Short-term investments
Investment Holdings [Line Items]
Other investments		1	57
Other investments
Investment Holdings [Line Items]
Other investments		$ 298	$ 133
[1]	Includes $4,586 in 2018 and $2,341 in 2017 of loan receivables and limited partnerships from consolidated variable interest entities

INVESTMENTS - Investments in Co

INVESTMENTS - Investments in Consolidated Variable Interest Entities (Detail) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost		$ 78,935	[1],[2]	$ 75,132	[3]
Available for sale, fixed maturity securities	[4]	85,881	[1],[2]	84,313	[3]
Equity securities	[4],[5]	1,103
Available for sale securities, equity securities				1,023
Other investments	[6]	5,831		3,402
Asset derivatives		457		331
Assets, fair value disclosure		91,289		89,215
Liability derivatives		367		474
Liabilities		118,186		112,619
Liabilities, fair value disclosure		367		474
Variable Interest Entity, Consolidated
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost	[7],[8]	4,492		4,538
Available for sale, fixed maturity securities	[7],[8]	5,202		5,509
Available-for-sale equity securities, amortized cost basis				606
Equity securities, FV-NI, cost		755
Equity securities		755
Available for sale securities, equity securities				753
Other investments	[9]	4,586		2,341
Other investments, fair value	[9]	4,577		2,328
Asset derivatives, amortized cost	[10]	202		151
Asset derivatives	[10]	202		151
Assets, amortized cost		10,035		7,636
Assets, fair value disclosure		10,736		8,741
Liability derivatives, amortized cost	[10]	92		128
Liability derivatives	[10]	92		128
Liabilities		92		128
Liabilities, fair value disclosure		$ 92		$ 128
[1]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[2]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[3]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[4]	Includes perpetual securities
[5]	Includes perpetual securities ($69 at fair value)
[6]	Includes $4,586 in 2018 and $2,341 in 2017 of loan receivables and limited partnerships from consolidated variable interest entities
[7]	Includes perpetual securities
[8]	Includes perpetual securities, see Notes 1 and 3 of the Notes to the Consolidated Financial Statements
[9]	Consists of TREs, CMLs, MMLs, and alternative investments in limited partnerships
[10]	Consists entirely of derivatives

INVESTMENTS - Investments in Va

INVESTMENTS - Investments in Variable Interest Entities Not Consolidated (Details) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost		$ 78,935	[1],[2]	$ 75,132	[3]
Available for sale, fixed maturity securities	[4]	85,881	[1],[2]	84,313	[3]
Securities held to maturity, fixed maturities, amortized cost		31,259		31,430
Held to maturity, fixed maturity securities, fair value		37,956		38,072
Other investments	[5]	5,831		3,402
Assets, fair value disclosure		91,289		89,215
Variable Interest Entity, Not Consolidated
Variable Interest Entity [Line Items]
Available for sale, fixed maturity securities, amortized cost	[6]	4,870		5,004
Available for sale, fixed maturity securities	[6]	5,358		5,724
Securities held to maturity, fixed maturities, amortized cost		2,469		2,549
Held to maturity, fixed maturity securities, fair value		2,795		2,929
Other investments		106		55
Other investments, fair value		106		55
Assets, amortized cost		7,445		7,608
Assets, fair value disclosure		$ 8,259		$ 8,708
[1]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[2]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[3]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[4]	Includes perpetual securities
[5]	Includes $4,586 in 2018 and $2,341 in 2017 of loan receivables and limited partnerships from consolidated variable interest entities
[6]	Includes perpetual securities

INVESTMENTS - Securities Lendin

INVESTMENTS - Securities Lending Transactions Accounted for as Secured Borrowings (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		$ 3,712	$ 606
Gross amount of recognized liabilities for securities lending		3,712	606
Amounts related to agreements not included in offsetting disclosure in Note 4		0	0
Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		3,295	49
Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		13	73
Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		60	54
Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		335	415
Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		9	15
Maturity Overnight and Continuous
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	417	557
Maturity Overnight and Continuous | Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	0	0
Maturity Overnight and Continuous | Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	13	73
Maturity Overnight and Continuous | Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	60	54
Maturity Overnight and Continuous | Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	335	415
Maturity Overnight and Continuous | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred	[1]	9	15
Maturity up to 30 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		2,942	49
Maturity up to 30 Days | Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		2,942	49
Maturity up to 30 Days | Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days | Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days | Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	0
Maturity up to 30 Days | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0	$ 0
Maturity 30 to 90 Days
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		353
Maturity 30 to 90 Days | Japan government and agencies
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		353
Maturity 30 to 90 Days | Public utilities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0
Maturity 30 to 90 Days | Banks/financial institutions
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0
Maturity 30 to 90 Days | Other corporate
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		0
Maturity 30 to 90 Days | Equity securities
Transfer of Certain Financial Assets Accounted for as Secured Borrowings [Line Items]
Securities Loaned, Including Not Subject to Master Netting Arrangement and Assets other than Securities Transferred		$ 0
[1]	These securities are pledged as collateral under the Company's U.S. securities lending program and can be called at its discretion; therefore, they are classified as Overnight and Continuous.

DERIVATIVE INSTRUMENTS - Additi

DERIVATIVE INSTRUMENTS - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018USD ($)yrcounterparties	Jun. 30, 2017USD ($)	Jun. 30, 2018USD ($)yrcounterparties	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Cash flow hedging activity, maximum time period | yr	8		8
Number of counterparties | counterparties	15		15
Number of counterparties that comprise majority of aggregate notional amount of swaps | counterparties	4		4
Percentage of notional amount of swaps from certain number of counterparties	60.00%		60.00%
Derivative, Net Liability Position, Aggregate Fair Value	$ 160		$ 160		$ 264
Additional Collateral, Aggregate Fair Value	36		36
Net investment hedge
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	$ 0	0	$ 0
2.40% senior notes due March 2020
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	550		550
4.00% senior notes due February 2022
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	350		350
3.625% senior notes due June 2023
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	700		700
3.625% senior notes due November 2024
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	750		750
3.25% senior notes due March 2025
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	$ 450		$ 450

DERIVATIVE INSTRUMENTS - Summar

DERIVATIVE INSTRUMENTS - Summary of Balance Sheet Classification of Derivative Fair Value Amounts, as well as Gross Asset and Liability Fair Value Amounts (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	$ 28,803	$ 25,751
Derivative asset, fair value, gross asset including not subject to master netting arrangement	457	331
Derivative liability, fair value, gross liability including not subject to master netting arrangement	(367)	(474)
Asset derivatives fair value	255	180
Liability derivatives fair value	(276)	(346)
Other assets
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	17,559	10,948
Asset derivatives fair value	457	331
Liability derivatives fair value	0	0
Other liabilities
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	11,244	14,803
Asset derivatives fair value	0	0
Liability derivatives fair value	(367)	(474)
Cash flow hedges
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	75	75
Asset derivatives fair value	1	0
Liability derivatives fair value	(4)	(8)
Cash flow hedges | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	75	75
Asset derivatives fair value	1	0
Liability derivatives fair value	(4)	(8)
Fair value hedges
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	12,535	15,310
Asset derivatives fair value	17	2
Liability derivatives fair value	(8)	(223)
Fair value hedges | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	3,310	7,640
Asset derivatives fair value	17	2
Liability derivatives fair value	(3)	(221)
Fair value hedges | Foreign currency options
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	9,225	7,670
Asset derivatives fair value	0	0
Liability derivatives fair value	(5)	(2)
Net investment hedge
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	0	439
Asset derivatives fair value	0	12
Liability derivatives fair value	0	(1)
Net investment hedge | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	0	5
Asset derivatives fair value	0	0
Liability derivatives fair value	0	0
Net investment hedge | Foreign currency options
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	0	434
Asset derivatives fair value	0	12
Liability derivatives fair value	0	(1)
Non-qualifying strategies
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	16,193	9,927
Asset derivatives fair value	439	317
Liability derivatives fair value	(355)	(242)
Non-qualifying strategies | Foreign currency swaps
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	5,390	5,386
Asset derivatives fair value	320	296
Liability derivatives fair value	(223)	(189)
Non-qualifying strategies | Foreign currency forwards
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	10,410	3,683
Asset derivatives fair value	119	20
Liability derivatives fair value	(132)	(53)
Non-qualifying strategies | Foreign currency options
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	303	770
Asset derivatives fair value	0	0
Liability derivatives fair value	0	0
Non-qualifying strategies | Credit default swaps
Derivatives, Fair Value [Line Items]
Net Derivatives Notional Amount	90	88
Asset derivatives fair value	0	1
Liability derivatives fair value	$ 0	$ 0

DERIVATIVE INSTRUMENTS - Gains

DERIVATIVE INSTRUMENTS - Gains (Losses) Recognized on Fair Value Hedging Relationships (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fixed-maturity securities and equity securities | Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives		$ (34)		$ 307
Gains (losses) on derivatives excluded from effectiveness testing		(50)		(98)
Gains (losses) on derivatives included in effectiveness testing		16		405
Gains (losses) recognized for hedged items		(15)		(387)
Ineffectiveness recognized for fair value hedge		1		18
Fixed maturity securities | Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives	$ (215)		$ 199
Gains (losses) on derivatives excluded from effectiveness testing	(30)		(69)
Gains (losses) on derivatives included in effectiveness testing	(185)		268
Gains (losses) recognized for hedged items	186		(278)
Ineffectiveness recognized for fair value hedge	1		(10)
Fixed maturity securities | Foreign currency options
Derivative Instruments, Gain (Loss) [Line Items]
Total gains (losses) recognized for derivatives	(2)	(7)	(3)	17
Gains (losses) on derivatives excluded from effectiveness testing	(2)	(7)	(3)	6
Gains (losses) on derivatives included in effectiveness testing	0	0	0	11
Gains (losses) recognized for hedged items	0	0	0	(10)
Ineffectiveness recognized for fair value hedge	$ 0	$ 0	$ 0	$ 1

DERIVATIVE INSTRUMENTS - Deriva

DERIVATIVE INSTRUMENTS - Derivatives and Hedging Instruments Gain (Loss) Summary (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized foreign currency translation gains (losses) during period		$ (493)	$ 9	$ 332	$ 383
Derivative gains (losses)		(172)	(51)	(28)	(103)
Derivative and non-derivative hedging instruments gain (loss) recognized in other comprehensive income effective portion before tax	[1]	53	9	(33)	(37)
Cash flow hedges
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		0	0	1	0
Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	[1]	(2)	(2)	4	1
Cash flow hedges | Foreign currency swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		0	0	1	0
Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	[1]	(2)	(2)	4	1
Fair value hedges
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		(31)	(56)	(82)	(73)
Fair value hedges | Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	[2]	(29)	(49)	(79)	(80)
Fair value hedges | Foreign currency options
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)	[2]	(2)	(7)	(3)	7
Net investment hedge
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		0	0	0	0
Unrealized foreign currency translation gains (losses) during period	[1]	55	11	(37)	(38)
Net investment hedge | Non-derivative hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		0	0	0	0
Unrealized foreign currency translation gains (losses) during period	[1]	55	(1)	(29)	(18)
Net investment hedge | Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		0	0	0	0
Unrealized foreign currency translation gains (losses) during period	[1]	0	(19)	0	(28)
Net investment hedge | Foreign currency options
Derivative Instruments, Gain (Loss) [Line Items]
Net Realized Investment Gains (Losses) Recognized in Income on Derivative (Ineffective Portion)		0	0	0	0
Unrealized foreign currency translation gains (losses) during period	[1]	0	31	(8)	8
Non-qualifying strategies
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		(141)	5	53	(30)
Non-qualifying strategies | Foreign currency swaps
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		14	34	28	26
Non-qualifying strategies | Foreign currency forwards
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		(154)	(29)	25	(56)
Non-qualifying strategies | Foreign currency options
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		$ (1)	$ 0	$ 0	$ 0
[1]	Cash flow hedge items are recorded as unrealized gains (losses) on derivatives and net investment hedge items are recorded in the unrealized foreign currency translation gains (losses) line in the consolidated statement of comprehensive income (loss).
[2]	Impact shown net of effect of hedged items (see Fair Value Hedges section of this Note 4 for further detail)

DERIVATIVE INSTRUMENTS - Fair V

DERIVATIVE INSTRUMENTS - Fair Value and Notional Amounts of Derivatives With Counterparty Credit Risk (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Derivatives	$ 28,803	$ 25,751
Asset Derivatives Fair Value	457	331
Liability Derivatives Fair Value	(367)	(474)
AA
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Derivatives	5,122	4,708
Asset Derivatives Fair Value	78	52
Liability Derivatives Fair Value	(12)	(37)
A
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Derivatives	23,237	20,604
Asset Derivatives Fair Value	375	271
Liability Derivatives Fair Value	(302)	(370)
BBB
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Notional Amount of Derivatives	444	439
Asset Derivatives Fair Value	4	8
Liability Derivatives Fair Value	$ (53)	$ (67)

DERIVATIVE INSTRUMENTS - Offset

DERIVATIVE INSTRUMENTS - Offsetting of Financial Assets and Derivative Assets (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Offsetting Assets [Line Items]
Gross amount of recognized derivative assets	$ 255	$ 180
Gross amount of liabilities offset in balance sheet	0	0
Net amount of derivative assets presented in the balance sheet	255	180
Financial instruments, amount not offset	(138)	(82)
Derivative, collateral, obligation to return securities	(32)	0
Derivative, collateral, obligation to return cash	(82)	(98)
Derivative asset, fair value, amount offset against collateral, subject to master netting agreement	3	0
Derivative asset, not subject to master netting arrangement	202	151
Derivative asset, fair value, amount offset against collateral, not subject to master netting agreement	202	151
Derivative asset, fair value, gross asset including not subject to master netting arrangement	457	331
Net amount of derivative assets presented in balance sheet	457	331
Derivative asset, fair value, amount offset against collateral	205	151
Gross amounts of recognized financial instruments	4,095	923
Gross amounts offset in balance sheet	0	0
Net amounts of assets presented in balance sheet	4,095	923
Carrying value of financial instruments not offset in balance sheet	(138)	(82)
Securities collateral, not offset in balance sheet	(32)	0
Cash collateral, not offset in balance sheet	(3,720)	(690)
Financial instruments, amount of assets offset against collateral	205	151
Securities lending and similar arrangements
Offsetting Assets [Line Items]
Gross amounts of recognized financial instruments	3,638	592
Gross amounts offset in balance sheet	0	0
Net amounts of assets presented in balance sheet	3,638	592
Carrying value of financial instruments not offset in balance sheet	0	0
Securities collateral, not offset in balance sheet	0	0
Cash collateral, not offset in balance sheet	(3,638)	(592)
Financial instruments, amount of assets offset against collateral	$ 0	$ 0

DERIVATIVE INSTRUMENTS - Offs56

DERIVATIVE INSTRUMENTS - Offsetting of Financial Liabilities and Derivative Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Offsetting Liabilities [Line Items]
Gross amount of recognized derivative liabilities	$ (276)	$ (346)
Gross amount of assets offset in balance sheet	0	0
Derivative liability, fair value, amount not offset against collateral	(276)	(346)
Financial instruments, amount not offset	138	82
Derivative, collateral, right to reclaim securities	73	245
Derivative, collateral, right to reclaim cash	51	10
Derivative liability, fair value, amount offset against collateral, subject to master netting agreement	(14)	(9)
Derivative liability, not subject to master netting arrangement	(91)	(128)
Derivative liability, fair value, amount offset against collateral, not subject to master netting agreement	(91)	(128)
Derivative liability, fair value, gross liability including not subject to master netting arrangement	(367)	(474)
Net amount of derivative liabilities presented in balance sheet	(367)	(474)
Derivative liability, fair value, amount offset against collateral	(105)	(137)
Gross Amounts of Recognized Financial Instruments, Offsetting Liabilities	(4,079)	(1,080)
Gross Amounts Offset in Statement of Financial Position, Offsetting Liabilities	0	0
Net Amounts of Financial Instruments Presented in Balance Sheet, Offsetting Liabilities	(4,079)	(1,080)
Carrying value of financial instruments, liabilities not offset in balance sheet	3,776	674
Securities Collateral, Liabilities Not Offset in Balance Sheet	73	245
Cash Collateral, Liabilities Not Offset in Balance Sheet	51	10
Financial instruments, amount of liabilities offset against collateral	(179)	(151)
Securities lending and similar arrangements
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Financial Instruments, Offsetting Liabilities	(3,712)	(606)
Gross Amounts Offset in Statement of Financial Position, Offsetting Liabilities	0	0
Net Amounts of Financial Instruments Presented in Balance Sheet, Offsetting Liabilities	(3,712)	(606)
Carrying value of financial instruments, liabilities not offset in balance sheet	3,638	592
Securities Collateral, Liabilities Not Offset in Balance Sheet	0	0
Cash Collateral, Liabilities Not Offset in Balance Sheet	0	0
Financial instruments, amount of liabilities offset against collateral	$ (74)	$ (14)

FAIR VALUE MEASUREMENTS - Fair

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Assets:
Available for sale, fixed maturity securities	[1]	$ 85,881	[2],[3]	$ 84,313	[4]
Equity securities	[1],[5]	1,103
Asset derivatives		457		331
Other Investments		1		57
Cash and cash equivalents		3,847		3,491
Total assets		91,289		89,215
Liabilities:
Liability derivatives		367		474
Total liabilities		367		474
Foreign currency swaps
Assets:
Asset derivatives		321		296
Liabilities:
Liability derivatives		227		197
Foreign currency forwards
Assets:
Asset derivatives		136		22
Liabilities:
Liability derivatives		135		274
Foreign currency options
Assets:
Asset derivatives				12
Liabilities:
Liability derivatives		5		3
Credit default swaps
Assets:
Asset derivatives				1
Fixed maturities
Assets:
Available for sale, fixed maturity securities	[1]	85,881		84,313
Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		35,116		31,230
Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		1,928		1,370
Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		347		444
Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		7,364		7,954
Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		1,743		1,909
Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		9,182		8,933
Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		30,201		32,473
Equity securities
Assets:
Equity securities, available-for-sale				1,023
Level 1
Assets:
Available for sale, fixed maturity securities		33,591		30,109
Equity securities		1,011
Asset derivatives		0		0
Other Investments		1		57
Cash and cash equivalents		3,847		3,491
Total assets		38,450		34,658
Liabilities:
Total liabilities		0		0
Level 1 | Foreign currency swaps
Assets:
Asset derivatives		0		0
Liabilities:
Liability derivatives		0		0
Level 1 | Foreign currency forwards
Assets:
Asset derivatives		0		0
Liabilities:
Liability derivatives		0		0
Level 1 | Foreign currency options
Assets:
Asset derivatives				0
Liabilities:
Liability derivatives		0		0
Level 1 | Credit default swaps
Assets:
Asset derivatives				0
Level 1 | Fixed maturities
Assets:
Available for sale, fixed maturity securities		33,591		30,109
Level 1 | Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		33,591		30,109
Level 1 | Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		0		0
Level 1 | Equity securities
Assets:
Equity securities, available-for-sale				1,001
Level 2
Assets:
Available for sale, fixed maturity securities		51,787		53,790
Equity securities		75
Asset derivatives		255		180
Other Investments		0		0
Cash and cash equivalents		0		0
Total assets		52,117		53,976
Liabilities:
Total liabilities		275		346
Level 2 | Foreign currency swaps
Assets:
Asset derivatives		119		146
Liabilities:
Liability derivatives		135		69
Level 2 | Foreign currency forwards
Assets:
Asset derivatives		136		22
Liabilities:
Liability derivatives		135		274
Level 2 | Foreign currency options
Assets:
Asset derivatives				12
Liabilities:
Liability derivatives		5		3
Level 2 | Credit default swaps
Assets:
Asset derivatives				0
Level 2 | Fixed maturities
Assets:
Available for sale, fixed maturity securities		51,787		53,790
Level 2 | Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		1,525		1,121
Level 2 | Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		1,928		1,370
Level 2 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		169		269
Level 2 | Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		7,258		7,886
Level 2 | Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		1,743		1,909
Level 2 | Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		9,159		8,908
Level 2 | Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		30,005		32,327
Level 2 | Equity securities
Assets:
Equity securities, available-for-sale				6
Level 3
Assets:
Available for sale, fixed maturity securities		503		414
Equity securities		17
Asset derivatives		202		151
Other Investments		0		0
Cash and cash equivalents		0		0
Total assets		722		581
Liabilities:
Total liabilities		92		128
Level 3 | Foreign currency swaps
Assets:
Asset derivatives		202		150
Liabilities:
Liability derivatives		92		128
Level 3 | Foreign currency forwards
Assets:
Asset derivatives		0		0
Liabilities:
Liability derivatives		0		0
Level 3 | Foreign currency options
Assets:
Asset derivatives				0
Liabilities:
Liability derivatives		0		0
Level 3 | Credit default swaps
Assets:
Asset derivatives				1
Level 3 | Fixed maturities
Assets:
Available for sale, fixed maturity securities		503		414
Level 3 | Fixed maturities | Government and agencies
Assets:
Available for sale, fixed maturity securities		0		0
Level 3 | Fixed maturities | Municipalities
Assets:
Available for sale, fixed maturity securities		0		0
Level 3 | Fixed maturities | Mortgage- and asset-backed securities
Assets:
Available for sale, fixed maturity securities		178		175
Level 3 | Fixed maturities | Public utilities
Assets:
Available for sale, fixed maturity securities		106		68
Level 3 | Fixed maturities | Sovereign and supranational
Assets:
Available for sale, fixed maturity securities		0		0
Level 3 | Fixed maturities | Banks/financial institutions
Assets:
Available for sale, fixed maturity securities		23		25
Level 3 | Fixed maturities | Other corporate
Assets:
Available for sale, fixed maturity securities		$ 196		146
Level 3 | Equity securities
Assets:
Equity securities, available-for-sale				$ 16
[1]	Includes perpetual securities
[2]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[3]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[4]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[5]	Includes perpetual securities ($69 at fair value)

FAIR VALUE MEASUREMENTS - Fai58

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets and Liabilities Carried at Cost or Amortized Cost (Details) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments	[1]	$ 5,831		$ 3,402
Assets:
Securities held to maturity, fixed maturities, amortized cost		31,259		31,430
Held to maturity, fixed maturity securities, fair value		37,956		38,072
Other investments carried at amortized cost		5,329	[2]	3,017	[3]
Other investments carried at amortized cost, fair value		5,316	[2]	3,002	[3]
Total financial instruments assets not carried at fair value		36,588		34,447
Assets fair value disclosure financial instruments carried at cost		43,272		41,074
Liabilities:
Other policyholder funds		7,140		6,939
Other policyholders' funds fair value disclosure		7,060		6,841
Notes payable		5,299		5,267
Notes payable fair value disclosure		5,380		5,553
Total financial instrument liabilities not carried at fair value		12,439		12,206
Liabilities fair value disclosure financial instruments carried at cost		12,440		12,394
Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		37,956		38,072
Government and agencies | Fixed maturities
Assets:
Securities held to maturity, fixed maturities, amortized cost		21,808		21,331
Held to maturity, fixed maturity securities, fair value		27,217		26,491
Municipalities | Fixed maturities
Assets:
Securities held to maturity, fixed maturities, amortized cost		363		357
Held to maturity, fixed maturity securities, fair value		474		462
Mortgage- and asset-backed securities | Fixed maturities
Assets:
Securities held to maturity, fixed maturities, amortized cost		16		26
Held to maturity, fixed maturity securities, fair value		17		27
Public utilities | Fixed maturities
Assets:
Securities held to maturity, fixed maturities, amortized cost		3,236		3,300
Held to maturity, fixed maturity securities, fair value		3,552		3,698
Sovereign and supranational | Fixed maturities
Assets:
Securities held to maturity, fixed maturities, amortized cost		1,557		1,523
Held to maturity, fixed maturity securities, fair value		1,843		1,835
Banks/financial institutions | Fixed maturities
Assets:
Securities held to maturity, fixed maturities, amortized cost		1,532		2,206
Held to maturity, fixed maturity securities, fair value		1,700		2,387
Other corporate | Fixed maturities
Assets:
Securities held to maturity, fixed maturities, amortized cost		2,747		2,687
Held to maturity, fixed maturity securities, fair value		3,153		3,172
Policy loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments		222		210
Equity method investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other investments		279		118
Level 1
Assets:
Other investments carried at amortized cost, fair value		0	[2]	0	[3]
Assets fair value disclosure financial instruments carried at cost		27,209		26,491
Liabilities:
Other policyholders' funds fair value disclosure		0		0
Notes payable fair value disclosure		0		0
Liabilities fair value disclosure financial instruments carried at cost		0		0
Level 1 | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		27,209		26,491
Level 1 | Government and agencies | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		27,209		26,491
Level 1 | Municipalities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 1 | Mortgage- and asset-backed securities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 1 | Public utilities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 1 | Sovereign and supranational | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 1 | Banks/financial institutions | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 1 | Other corporate | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 2
Assets:
Other investments carried at amortized cost, fair value		19	[2]	15	[3]
Assets fair value disclosure financial instruments carried at cost		10,749		11,577
Liabilities:
Other policyholders' funds fair value disclosure		0		0
Notes payable fair value disclosure		5,110		5,288
Liabilities fair value disclosure financial instruments carried at cost		5,110		5,288
Level 2 | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		10,730		11,562
Level 2 | Government and agencies | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		8		0
Level 2 | Municipalities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		474		462
Level 2 | Mortgage- and asset-backed securities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		8
Level 2 | Public utilities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		3,552		3,698
Level 2 | Sovereign and supranational | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		1,843		1,835
Level 2 | Banks/financial institutions | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		1,700		2,387
Level 2 | Other corporate | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		3,153		3,172
Level 3
Assets:
Other investments carried at amortized cost, fair value		5,297	[2]	2,987	[3]
Assets fair value disclosure financial instruments carried at cost		5,314		3,006
Liabilities:
Other policyholders' funds fair value disclosure		7,060		6,841
Notes payable fair value disclosure		270		265
Liabilities fair value disclosure financial instruments carried at cost		7,330		7,106
Level 3 | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		17		19
Level 3 | Government and agencies | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 3 | Municipalities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 3 | Mortgage- and asset-backed securities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		17		19
Level 3 | Public utilities | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 3 | Sovereign and supranational | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 3 | Banks/financial institutions | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		0		0
Level 3 | Other corporate | Fixed maturities
Assets:
Held to maturity, fixed maturity securities, fair value		$ 0		$ 0
[1]	Includes $4,586 in 2018 and $2,341 in 2017 of loan receivables and limited partnerships from consolidated variable interest entities
[2]	Excludes policy loans of $222 and equity method investments of $279, at carrying value
[3]	Excludes policy loans of $210 and equity method investments of $118, at carrying value

FAIR VALUE MEASUREMENTS - Fai59

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets by Pricing Source, Securities Carried at Fair Value (Details) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities	[1]	$ 85,881	[2],[3]	$ 84,313	[4]
Equity securities	[1],[5]	1,103
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		33,591		30,109
Equity securities		1,011
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		51,787		53,790
Equity securities		75
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		503		414
Equity securities		17
Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		1,036
Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		961
Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		75
Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		0
Net asset value valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		67
Net asset value valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		50
Net asset value valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		0
Net asset value valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		17
Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities	[1]	85,881		84,313
Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		33,591		30,109
Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		51,787		53,790
Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		503		414
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				1,023
Equity securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				1,001
Equity securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				6
Equity securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				16
Equity securities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				1,007
Equity securities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				1,001
Equity securities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				6
Equity securities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				0
Equity securities | Net asset value valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				16
Equity securities | Net asset value valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				0
Equity securities | Net asset value valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				0
Equity securities | Net asset value valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities, available-for-sale				16
Government and agencies | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		35,116		31,230
Government and agencies | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		33,591		30,109
Government and agencies | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,525		1,121
Government and agencies | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		35,116		31,230
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		33,591		30,109
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,525		1,121
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Municipalities | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,928		1,370
Municipalities | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Municipalities | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,928		1,370
Municipalities | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Municipalities | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,928		1,370
Municipalities | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Municipalities | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,928		1,370
Municipalities | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		178		175
Mortgage- and asset-backed securities | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		347		444
Mortgage- and asset-backed securities | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Mortgage- and asset-backed securities | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		169		269
Mortgage- and asset-backed securities | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		178		175
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		169		269
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		169		269
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		178		175
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		178		175
Public utilities | Discounted cash flow technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		106		68
Public utilities | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		7,364		7,954
Public utilities | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Public utilities | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		7,258		7,886
Public utilities | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		106		68
Public utilities | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		7,258		7,886
Public utilities | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Public utilities | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		7,258		7,886
Public utilities | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Public utilities | Fixed maturities | Discounted cash flow technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		106		68
Public utilities | Fixed maturities | Discounted cash flow technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Public utilities | Fixed maturities | Discounted cash flow technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Public utilities | Fixed maturities | Discounted cash flow technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		106		68
Sovereign and supranational | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,743		1,909
Sovereign and supranational | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Sovereign and supranational | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,743		1,909
Sovereign and supranational | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,743		1,807
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		1,743		1,807
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Sovereign and supranational | Fixed maturities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities				102
Sovereign and supranational | Fixed maturities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities				0
Sovereign and supranational | Fixed maturities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities				102
Sovereign and supranational | Fixed maturities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities				0
Banks/financial institutions | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		23		25
Banks/financial institutions | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		9,182		8,933
Banks/financial institutions | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Banks/financial institutions | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		9,159		8,908
Banks/financial institutions | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		23		25
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		8,959		8,908
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		8,959		8,908
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Banks/financial institutions | Fixed maturities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		223		25
Banks/financial institutions | Fixed maturities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Banks/financial institutions | Fixed maturities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		200		0
Banks/financial institutions | Fixed maturities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		23		25
Other corporate | Discounted cash flow technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		196		146
Other corporate | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		30,201		32,473
Other corporate | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Other corporate | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		30,005		32,327
Other corporate | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		196		146
Other corporate | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		30,005		32,327
Other corporate | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Other corporate | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		30,005		32,327
Other corporate | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Other corporate | Fixed maturities | Discounted cash flow technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		196		146
Other corporate | Fixed maturities | Discounted cash flow technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Other corporate | Fixed maturities | Discounted cash flow technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		0		0
Other corporate | Fixed maturities | Discounted cash flow technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, fixed maturity securities		$ 196		$ 146
[1]	Includes perpetual securities
[2]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[3]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[4]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[5]	Includes perpetual securities ($69 at fair value)

FAIR VALUE MEASUREMENTS - Fai60

FAIR VALUE MEASUREMENTS - Fair Value Hierarchy Levels of Assets by Pricing Source, Securities Carried at Amortized Cost (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	$ 37,956	$ 38,072
Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	37,956	38,072
Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,209	26,491
Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	10,730	11,562
Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	17	19
Government and agencies | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,217	26,491
Government and agencies | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,209	26,491
Government and agencies | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	8	0
Government and agencies | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,217	26,491
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	27,209	26,491
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	8	0
Government and agencies | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	474	462
Municipalities | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	474	462
Municipalities | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	474	462
Municipalities | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Municipalities | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	474	462
Municipalities | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	17	27
Mortgage- and asset-backed securities | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	8
Mortgage- and asset-backed securities | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	17	19
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value		8
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value		0
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value		8
Mortgage- and asset-backed securities | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value		0
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	17	19
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Mortgage- and asset-backed securities | Fixed maturities | Consensus pricing valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	17	19
Public utilities | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,552	3,698
Public utilities | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Public utilities | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,552	3,698
Public utilities | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Public utilities | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,552	3,698
Public utilities | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Public utilities | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,552	3,698
Public utilities | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,843	1,835
Sovereign and supranational | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,843	1,835
Sovereign and supranational | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,843	1,835
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,843	1,835
Sovereign and supranational | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,700	2,387
Banks/financial institutions | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,700	2,387
Banks/financial institutions | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,700	2,387
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	1,700	2,387
Banks/financial institutions | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate | Fixed maturities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,153	3,172
Other corporate | Fixed maturities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate | Fixed maturities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,153	3,172
Other corporate | Fixed maturities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate | Fixed maturities | Third party pricing vendor valuation technique
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,153	3,172
Other corporate | Fixed maturities | Third party pricing vendor valuation technique | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	0	0
Other corporate | Fixed maturities | Third party pricing vendor valuation technique | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	3,153	3,172
Other corporate | Fixed maturities | Third party pricing vendor valuation technique | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held to maturity, fixed maturity securities, fair value	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Chang

FAIR VALUE MEASUREMENTS - Changes in Investments and Derivatives Carried at Fair Value Classified as Level 3 (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		$ 607	$ 295	$ 453	$ 223
Realized investment gains (losses) included in earnings		(43)	(10)	83	28
Unrealized gains (losses) included in other comprehensive income (loss)		(13)	1	0	8
Purchases		81	87	97	124
Issuances		0	0	0	0
Sales		0	0	0	(1)
Settlements		(2)	(7)	(3)	(16)
Transfers into Level 3		0	0	0	0
Transfers out of Level 3		0	0	0	0
Balance, end of period		630	366	630	366
Change in unrealized gains (losses) still held		(43)	(10)	83	28
Foreign currency swaps
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	[1]	154	19	22	(21)
Realized gains or losses included in earnings	[1]	(42)	(10)	84	28
Unrealized gains or losses included in other comprehensive income (loss)	[1]	(2)	(2)	4	0
Purchases	[1]	0	0	0	0
Issuances	[1]	0	0	0	0
Sales	[1]	0	0	0	0
Settlements	[1]	0	0	0	0
Transfers into Level 3	[1]	0	0	0	0
Transfers out of Level 3	[1]	0	0	0	0
Balance, end of period	[1]	110	7	110	7
Changes in unrealized gain (losses) still held	[1]	(42)	(10)	84	28
Credit default swaps
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance, beginning of period	[1]	1	2	1	2
Realized gains or losses included in earnings	[1]	(1)	0	(1)	0
Unrealized gains or losses included in other comprehensive income (loss)	[1]	0	0	0	0
Purchases	[1]	0	0	0	0
Issuances	[1]	0	0	0	0
Sales	[1]	0	0	0	0
Settlements	[1]	0	0	0	0
Transfers into Level 3	[1]	0	0	0	0
Transfers out of Level 3	[1]	0	0	0	0
Balance, end of period	[1]	0	2	0	2
Changes in unrealized gain (losses) still held	[1]	(1)	0	(1)	0
Fixed maturities | Mortgage- and asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		186	195	175	198
Realized investment gains (losses) included in earnings		0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)		(8)	0	3	6
Purchases		0	0	0	0
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		0	(7)	0	(16)
Transfers into Level 3		0	0	0	0
Transfers out of Level 3		0	0	0	0
Balance, end of period		178	188	178	188
Change in unrealized gains (losses) still held		0	0	0	0
Fixed maturities | Public utilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		83	16	68	16
Realized investment gains (losses) included in earnings		0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)		(1)	0	(2)	0
Purchases		24	37	40	37
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		0	0	0	0
Transfers into Level 3		0	0	0	0
Transfers out of Level 3		0	0	0	0
Balance, end of period		106	53	106	53
Change in unrealized gains (losses) still held		0	0	0	0
Fixed maturities | Banks/financial institutions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		24	24	25	25
Realized investment gains (losses) included in earnings		0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)		(1)	1	(2)	0
Purchases		0	0	0	0
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		0	0	0	0
Transfers into Level 3		0	0	0	0
Transfers out of Level 3		0	0	0	0
Balance, end of period		23	25	23	25
Change in unrealized gains (losses) still held		0	0	0	0
Fixed maturities | Other corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		143	35	146	0
Realized investment gains (losses) included in earnings		0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)		(1)	2	(3)	2
Purchases		56	40	56	75
Issuances		0	0	0	0
Sales		0	0	0	0
Settlements		(2)	0	(3)	0
Transfers into Level 3		0	0	0	0
Transfers out of Level 3		0	0	0	0
Balance, end of period		196	77	196	77
Change in unrealized gains (losses) still held		0	0	0	0
Equity securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period		16	4	16	3
Realized investment gains (losses) included in earnings		0	0	0	0
Unrealized gains (losses) included in other comprehensive income (loss)		0	0	0	0
Purchases		1	10	1	12
Issuances		0	0	0	0
Sales		0	0	0	(1)
Settlements		0	0	0	0
Transfers into Level 3		0	0	0	0
Transfers out of Level 3		0	0	0	0
Balance, end of period		17	14	17	14
Change in unrealized gains (losses) still held		$ 0	$ 0	$ 0	$ 0
[1]	Derivative assets and liabilities are presented net

FAIR VALUE MEASUREMENTS - Fai62

FAIR VALUE MEASUREMENTS - Fair Value Measurement Inputs and Valuation Techniques (Details) $ in Millions		Jun. 30, 2018USD ($)		Dec. 31, 2017USD ($)
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities	[1]	$ 85,881	[2],[3]	$ 84,313	[4]
Available for sale securities, equity securities				1,023
Equity securities	[1],[5]	1,103
Asset derivatives		457		331
Liability derivatives		367		474
Assets, fair value disclosure		91,289		89,215
Liabilities, fair value disclosure		367		474
Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		503		414
Equity securities		17
Asset derivatives		202		151
Assets, fair value disclosure		722		581
Liabilities, fair value disclosure		92		128
Net asset value valuation technique
Fair Value Measurement Inputs and Valuation Techniques
Equity securities		67
Net asset value valuation technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale securities, equity securities				16
Equity securities		17
Foreign currency swaps
Fair Value Measurement Inputs and Valuation Techniques
Asset derivatives		321		296
Liability derivatives		227		197
Foreign currency swaps | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Asset derivatives		202		150
Liability derivatives		92		128
Foreign currency swaps | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Asset derivatives		145		80
Liability derivatives		88		120
Foreign currency swaps | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Asset derivatives		57		70
Liability derivatives		$ 4		$ 8
Foreign currency swaps | Credit Spread | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input		0.0015		0.0009
Derivative liability, measurement input		0.0034		0.0013
Foreign currency swaps | Credit Spread | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input		0.0105		0.0090
Derivative liability, measurement input		0.0188		0.0157
Credit default swaps
Fair Value Measurement Inputs and Valuation Techniques
Asset derivatives				$ 1
Credit default swaps | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Asset derivatives				1
Credit default swaps | Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Asset derivatives				$ 1
Credit default swaps | Credit Spread | Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input				0.0025
Credit default swaps | Base Correlation | Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[6]			0.4633
Credit default swaps | Base Correlation | Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[6]			0.4965
Credit default swaps | Recovery Rate | Fair Value, Unobservable Input, Base Correlation, CDS Spreads, Recovery Rate | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input				0.3724
Dollar-denominated
Fair Value Measurement Inputs and Valuation Techniques
Available for sale securities, equity securities				$ 328
Equity securities		$ 391
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[7]	0.0292
Derivative liability, measurement input	[7]	0.0292
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[7]			0.0240
Derivative liability, measurement input	[7]			0.0240
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[7]			0.0254
Derivative liability, measurement input	[7]			0.0254
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[7]	0.0292
Derivative liability, measurement input	[7]	0.0292
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[7]			0.0240
Derivative liability, measurement input	[7]			0.0240
Dollar-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[7]			0.0254
Derivative liability, measurement input	[7]			0.0254
Yen-denominated
Fair Value Measurement Inputs and Valuation Techniques
Available for sale securities, equity securities				$ 695
Equity securities		$ 712
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[8]	0.0025		0.0026
Derivative liability, measurement input	[8]	0.0025		0.0026
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD), Interest Rates (JPY) and CDS Spreads | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[8]	0.0075		0.0085
Derivative liability, measurement input	[8]	0.0075		0.0085
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Lower Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[8]	0.0025		0.0026
Derivative liability, measurement input	[8]	0.0025		0.0026
Yen-denominated | Foreign currency swaps | Discount Rate | Fair Value, Unobservable Input, Interest Rates (USD) and Interest Rates (JPY) | Upper Limit | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Derivative asset, measurement input	[8]	0.0075		0.0085
Derivative liability, measurement input	[8]	0.0075		0.0085
Mortgage- and asset-backed securities | Consensus pricing valuation technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 178		$ 175
Banks/financial institutions | Consensus pricing valuation technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		23		25
Public utilities | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		106		68
Other corporate | Discounted cash flow technique | Level 3
Fair Value Measurement Inputs and Valuation Techniques
Available for sale, fixed maturity securities		$ 196		$ 146
[1]	Includes perpetual securities
[2]	Includes perpetual securities ($1,446 at amortized cost and $1,612 at fair value)
[3]	Includes perpetual securities, categorized in accordance with their respective economic maturities (the expected maturity date created by the combination of features in the financial instrument)
[4]	Includes perpetual securities ($1,462 at amortized cost and $1,789 at fair value)
[5]	Includes perpetual securities ($69 at fair value)
[6]	Range of base correlation for the Company's bespoke tranche for attachment and detachment points corresponding to market indices
[7]	Inputs derived from U.S. long-term rates to accommodate long maturity nature of the Company's swaps
[8]	Inputs derived from Japan long-term rates to accommodate long maturity nature of the Company's swaps

FAIR VALUE MEASUREMENTS - Addit

FAIR VALUE MEASUREMENTS - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0	$ 0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	$ 0	$ 0

POLICY LIABILITIES - Changes in

POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Liability for Unpaid Claims and Claims Expenses
Net balance, beginning of period			$ 4,392
Less claims paid during the period on claims incurred during:
Net balance, end of period	$ 4,524		4,524
Total liability for unpaid policy claims	4,524	$ 4,281	4,524	$ 4,281
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of period	4,041	3,854	3,881	3,707
Less reinsurance recoverables	31	30	28	27
Net balance, beginning of period	4,010	3,824	3,853	3,680
Add claims incurred during the period related to:
Current year	1,779	1,772	3,621	3,520
Prior years	(133)	(138)	(325)	(260)
Total incurred	1,646	1,634	3,296	3,260
Less claims paid during the period on claims incurred during:
Current year	1,226	1,220	1,746	1,721
Prior years	426	400	1,540	1,461
Total paid	1,652	1,620	3,286	3,182
Effect of foreign exchange rate changes on unpaid claims	(91)	4	50	84
Net balance, end of period	3,913	3,842	3,913	3,842
Add reinsurance recoverables	29	30	29	30
Total liability for unpaid policy claims	3,942	3,872	3,942	3,872
Life insurance
Less claims paid during the period on claims incurred during:
Total liability for unpaid policy claims	$ 582	$ 409	$ 582	$ 409

POLICY LIABILITIES - Additional

POLICY LIABILITIES - Additional Information (Details) - Health insurance - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Liability for Future Policy Benefit, by Product Segment [Line Items]
Prior years claims and claims adjustment expense	$ (133)	$ (138)	$ (325)	$ (260)
Aflac Japan
Liability for Future Policy Benefit, by Product Segment [Line Items]
Prior years claims and claims adjustment expense			$ (210)
Percentage of total prior year claims and claims adjustment expense			65.00%
Liability for unpaid claims and claims adjustment expense, foreign currency translation gain (loss)			$ (10)
Prior year claims and claims adjustment expense excluding effect of foreign currency			$ (200)
Percentage of total prior year claims and claims adjustment expense excluding effect of foreign currency			62.00%

REINSURANCE - Additional Infor

REINSURANCE - Additional Information (Details) $ in Millions, ¥ in Billions	6 Months Ended
	Jun. 30, 2018JPY (¥)	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Effects of Reinsurance [Line Items]
Percent change in spot yen/dollar exchange rate		2.20%
Percent change in ceded reserves		0.70%
Aflac Japan
Effects of Reinsurance [Line Items]
Committed reinsurance facility | ¥	¥ 110
Aflac Japan | Closed Block
Effects of Reinsurance [Line Items]
Reinsurance deferred profit liability		$ 1,000
Reinsurance recoverable		$ 935	$ 908

REINSURANCE - Effect of Reinsu

REINSURANCE - Effect of Reinsurance on Premiums and Benefits and Claims (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Effects of Reinsurance [Line Items]
Direct premium income	$ 4,793	$ 4,752	$ 9,626	$ 9,476
Net premium income	4,706	4,665	9,450	9,303
Direct benefits and claims	3,106	3,117	6,225	6,246
Benefits and claims, net	3,031	3,039	6,073	6,091
All other
Effects of Reinsurance [Line Items]
Ceded premiums	(16)	(13)	(30)	(25)
Assumed premiums earned	2	1	3	3
Ceded benefits and claims	(12)	(11)	(23)	(22)
Assumed benefits and claims from other companies	2	0	1	2
Aflac Japan
Effects of Reinsurance [Line Items]
Net premium income	3,227	3,222	6,490	6,416
Aflac Japan | Closed Block
Effects of Reinsurance [Line Items]
Ceded premiums	(126)	(130)	(256)	(260)
Assumed premiums earned	53	55	107	109
Ceded benefits and claims	(114)	(119)	(231)	(241)
Assumed benefits and claims from other companies	49	52	101	106
Intercompany eliminations
Effects of Reinsurance [Line Items]
Ceded benefits and claims	11	13	23	26
Assumed benefits and claims from other companies	$ (11)	$ (13)	$ (23)	$ (26)

NOTES PAYABLE - Additional Info

NOTES PAYABLE - Additional Information (Details) $ in Millions	Jun. 30, 2018USD ($)
Lines of credit
Debt Instrument [Line Items]
Debt instrument, debt default, amount	$ 0
Notes Payable
Debt Instrument [Line Items]
Debt instrument, debt default, amount	$ 0

NOTES PAYABLE - Summary of Note

NOTES PAYABLE - Summary of Notes Payable (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Notes payable	$ 5,315	$ 5,289
2.40% senior notes due March 2020
Debt Instrument [Line Items]
Notes payable	549	548
4.00% senior notes due February 2022
Debt Instrument [Line Items]
Notes payable	348	348
3.625% senior notes due June 2023
Debt Instrument [Line Items]
Notes payable	697	697
3.625% senior notes due November 2024
Debt Instrument [Line Items]
Notes payable	746	745
3.25% senior notes due March 2025
Debt Instrument [Line Items]
Notes payable	446	446
2.875% senior notes due October 2026
Debt Instrument [Line Items]
Notes payable	297	297
6.90% senior notes due December 2039
Debt Instrument [Line Items]
Notes payable	220	220
6.45% senior notes due August 2040
Debt Instrument [Line Items]
Notes payable	254	254
4.00% senior notes due October 2046
Debt Instrument [Line Items]
Notes payable	394	394
.932% senior notes due January 2027
Debt Instrument [Line Items]
Notes payable	540	528
2.108% subordinated notes due October 2047
Debt Instrument [Line Items]
Notes payable	538	526
Yen-denominated loan variable interest rate due September 2021
Debt Instrument [Line Items]
Notes payable	45	44
Yen-denominated loan variable interest rate due September 2023
Debt Instrument [Line Items]
Notes payable	225	220
Capitalized lease obligations
Debt Instrument [Line Items]
Notes payable	$ 16	$ 22

NOTES PAYABLE - Summary of No70

NOTES PAYABLE - Summary of Notes Payable (Parenthetical) (Details) $ in Millions, ¥ in Billions	Jun. 30, 2018USD ($)	Jun. 30, 2018JPY (¥)	Dec. 31, 2017JPY (¥)
2.40% senior notes due March 2020
Debt Instrument [Line Items]
Debt instrument, interest rate	2.40%	2.40%	2.40%
Debt instrument, principal amount	$ 550
4.00% senior notes due February 2022
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%	4.00%	4.00%
Debt instrument, principal amount	$ 350
3.625% senior notes due June 2023
Debt Instrument [Line Items]
Debt instrument, interest rate	3.625%	3.625%	3.625%
Debt instrument, principal amount	$ 700
3.625% senior notes due November 2024
Debt Instrument [Line Items]
Debt instrument, interest rate	3.625%	3.625%	3.625%
Debt instrument, principal amount	$ 750
3.25% senior notes due March 2025
Debt Instrument [Line Items]
Debt instrument, interest rate	3.25%	3.25%	3.25%
Debt instrument, principal amount	$ 450
2.875% senior notes due October 2026
Debt Instrument [Line Items]
Debt instrument, interest rate	2.875%	2.875%	2.875%
6.90% senior notes due December 2039
Debt Instrument [Line Items]
Debt instrument, interest rate	6.90%	6.90%	6.90%
6.45% senior notes due August 2040
Debt Instrument [Line Items]
Debt instrument, interest rate	6.45%	6.45%	6.45%
4.00% senior notes due October 2046
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%	4.00%	4.00%
.932% senior notes due January 2027
Debt Instrument [Line Items]
Debt instrument, interest rate	0.932%	0.932%	0.932%
Debt instrument, principal amount | ¥		¥ 60	¥ 60
2.108% subordinated notes due October 2047
Debt Instrument [Line Items]
Debt instrument, interest rate	2.108%	2.108%	2.108%
Debt instrument, principal amount | ¥		¥ 60	¥ 60
Yen-denominated loan variable interest rate due September 2021
Debt Instrument [Line Items]
Debt instrument, interest rate	0.32%	0.32%	0.32%
Debt instrument, principal amount | ¥		¥ 5	¥ 5
Yen-denominated loan variable interest rate due September 2023
Debt Instrument [Line Items]
Debt instrument, interest rate	0.47%	0.47%	0.47%
Debt instrument, principal amount | ¥		¥ 25	¥ 25

NOTES PAYABLE - Summary of Line

NOTES PAYABLE - Summary of Lines of Credit (Details) - 6 months ended Jun. 30, 2018 ¥ in Millions, $ in Millions	USD ($)	JPY (¥)
$100 million line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	The rate quoted by the bank and agreed upon at the time of borrowing
Line of credit facility term	364 days
Line of credit facility, maximum borrowing capacity | $	$ 100
Line of credit facility, amount outstanding | $	$ 0
100.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	A rate per annum equal to (a) Tokyo interbank market rate (TIBOR) plus, the alternative applicable TIBOR margin during the availability period from the closing date to the commitment termination date or (b) the TIBOR rate offered by the agent to major banks in yen for the applicable period plus, the applicable alternative TIBOR margin during the term out period
Line of credit facility term	3 years
Line of credit facility, maximum borrowing capacity | ¥		¥ 100,000
Line of credit facility, amount outstanding | ¥		0
55.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	A rate per annum equal to, at the Company's option, either, (a) London Interbank Offered Rate (LIBOR) adjusted for certain costs or (b) a base rate determined by reference to the highest of (1) the federal funds rate plus 1/2 of 1%, (2) the rate of interest for such day announced by Mizuho Bank, Ltd. as its prime rate, or (3) the eurocurrency rate for an interest period of one month plus 1.00%, in each case plus an applicable margin
Line of credit facility term	5 years
Line of credit facility, maximum borrowing capacity | ¥		55,000
Line of credit facility, amount outstanding | ¥		0
$50 million line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	A rate per annum equal to, at the Parent Company's option, either (a) a eurocurrency rate determined by reference to the agent's LIBOR for the interest period relevant to such borrowing or (b) the base rate determined by reference to the greater of (i) the prime rate as determined by the agent, and (ii) the sum of 0.50% and the federal funds rate for such day
Line of credit facility, maximum borrowing capacity | $	$ 50
Line of credit facility, amount outstanding | $	$ 0
$250 million line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	USD three-month LIBOR plus 75 basis points per annum
Line of credit facility term	364 days
Line of credit facility, maximum borrowing capacity | $	$ 250
Line of credit facility, amount outstanding | $	$ 0
Debt instrument, term	3 months
37.5 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, interest rate description	Three-month TIBOR plus 80 basis points per annum
Line of credit facility term	364 days
Line of credit facility, maximum borrowing capacity | ¥		37,500
Line of credit facility, amount outstanding | ¥		¥ 0
Debt instrument, term	3 months
Lower Limit | 100.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.30%
Lower Limit | 55.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.085%
Upper Limit | $100 million line of credit
Line of Credit Facility [Line Items]
Debt instrument, term	3 months
Upper Limit | 100.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.50%
Upper Limit | 55.0 billion yen line of credit
Line of Credit Facility [Line Items]
Line of credit facility, commitment fee percentage	0.225%
Upper Limit | $50 million line of credit
Line of Credit Facility [Line Items]
Debt instrument, term	3 months

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Income Taxes [Line Items]
U.S. federal statutory corporate income tax rate	21.00%		35.00%	21.00%	35.00%
Income Tax Expense, Gross, Continuing Operations, Adjustment of Deferred Tax Assets		$ 1,000
Income Tax Benefit, Gross, Continuing Operations, Adjustment of Deferred Tax Liabilities		2,900
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax Asset (Liability)		(1,900)
Deferred Tax Assets, Valuation Allowance		700			$ 700
Aflac Japan
Income Taxes [Line Items]
Deferred Tax Liabilities, Net		$ 4,500			$ 4,500

SHAREHOLDERS' EQUITY - Reconcil

SHAREHOLDERS' EQUITY - Reconciliation of Number of Shares of Common Stock (Detail) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Common Stock Issued [Roll Forward]
Balance, beginning of period	1,345,762	1,342,498
Exercise of stock options and issuance of restricted shares	1,299	1,576
Balance, end of period	1,347,061	1,344,074
Treasury Stock [Roll Forward]
Balance, beginning of period	564,852	530,877
Balance, end of period	577,789	552,077
Shares outstanding, end of period	769,272	791,997
Treasury Stock
Treasury Stock [Roll Forward]
Stock acquired in open market, shares	13,441	22,310
Other purchases	328	346
Shares issued to AFL Stock Plan	(400)	(998)
Exercise of stock options	(327)	(414)
Other dispositions	(105)	(44)

SHAREHOLDERS' EQUITY - Anti-Dil

SHAREHOLDERS' EQUITY - Anti-Dilutive Share-Based Awards Excluded from Calculation of Diluted Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stockholders' Equity Note [Abstract]
Anti-dilutive share-based awards	48	838	28	740

SHAREHOLDERS' EQUITY - Addition

SHAREHOLDERS' EQUITY - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Feb. 28, 2018	Aug. 31, 2017
Stockholders Equity Note [Line Items]
Common stock, share repurchase, dollar amount	$ 601	$ 813
Remaining common stock available for purchase under share repurchase authorizations	84.6
Share Repurchase Program
Stockholders Equity Note [Line Items]
Stock acquired in open market, shares	13.4	22.4
Common stock, share repurchase, dollar amount	$ 601	$ 800
Share Repurchase Authorization 2017
Stockholders Equity Note [Line Items]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased, Before Stock Split				40
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			80

SHAREHOLDERS' EQUITY - Changes

SHAREHOLDERS' EQUITY - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	$ 3,685	$ 2,632	$ 4,028		$ 2,630
Other comprehensive income loss before reclassifications net of tax	[1]	(857)	765	(1,426)	[2]	755
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	24	4	24		16
Other comprehensive income (loss), net of tax	[1]	(833)	769	(1,402)		771
Balance, end of period	[1]	2,852	3,401	2,852		3,401
Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			(148)
Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			374
Unrealized foreign currency translation gains (losses)
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	(1,303)	(1,650)	(1,750)		(1,983)
Other comprehensive income loss before reclassifications net of tax	[1]	(463)	70	309	[2]	403
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	0	0	0		0
Other comprehensive income (loss), net of tax	[1]	(463)	70	309		403
Balance, end of period	[1]	(1,766)	(1,580)	(1,766)		(1,580)
Unrealized foreign currency translation gains (losses) | Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			0
Unrealized foreign currency translation gains (losses) | Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			(325)
Unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	5,206	4,474	5,964		4,805
Other comprehensive income loss before reclassifications net of tax	[1]	(391)	698	(1,733)	[2]	357
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	21	1	19		11
Other comprehensive income (loss), net of tax	[1]	(370)	699	(1,714)		368
Balance, end of period	[1]	4,836	5,173	4,836		5,173
Unrealized gains (losses) on investment securities | Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			(148)
Unrealized gains (losses) on investment securities | Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			734
Unrealized gains (losses) on derivatives
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	(21)	(22)	(23)		(24)
Other comprehensive income loss before reclassifications net of tax	[1]	(2)	(1)	3	[2]	1
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	0	0	0		0
Other comprehensive income (loss), net of tax	[1]	(2)	(1)	3		1
Balance, end of period	[1]	(23)	(23)	(23)		(23)
Unrealized gains (losses) on derivatives | Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			0
Unrealized gains (losses) on derivatives | Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			(3)
Pension liability adjustment
Accumulated Other Comprehensive Income [Roll Forward]
Balance, beginning of period	[1]	(197)	(170)	(163)		(168)
Other comprehensive income loss before reclassifications net of tax	[1]	(1)	(2)	(5)	[2]	(6)
Amounts reclassified from accumulated other comprehensive income net of tax	[1]	3	3	5		5
Other comprehensive income (loss), net of tax	[1]	2	1	0		(1)
Balance, end of period	[1]	$ (195)	$ (169)	(195)		$ (169)
Pension liability adjustment | Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			0
Pension liability adjustment | Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income [Roll Forward]
Amounts reclassified from accumulated other comprehensive income net of tax	[1]			$ (32)
[1]	All amounts in the table above are net of tax.
[2]	Amounts have been corrected to exclude the cumulative effects of changes in accounting principles for financial instruments and the tax effects from tax reform as identified in the rollforward of Accumulated Other Comprehensive Income within the Consolidated Statements of Shareholder’s Equity.

SHAREHOLDERS' EQUITY - Reclassi

SHAREHOLDERS' EQUITY - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended				6 Months Ended				12 Months Ended
		Jan. 31, 2018	Jun. 30, 2018		Jun. 30, 2017		Jun. 30, 2018		Jun. 30, 2017		Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses realized			$ (5)				$ (12)
Other than temporary impairment losses realized					$ (9)				$ (19)
Other gains (losses)	[1]		8		(47)		(119)		(177)
Total before tax			1,131		1,045		2,114		1,944
Income tax (expense) or benefit			(299)		(332)		(564)		(639)
Net of tax			$ 832		$ 713		$ 1,550		1,305
Blended statutory income tax rate			26.00%				27.00%
U.S. federal statutory corporate income tax rate		21.00%			35.00%		21.00%				35.00%
Reclassification Out Of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net of tax			$ (24)		$ (4)		$ (24)		(16)
Reclassification Out Of Accumulated Other Comprehensive Income | Unrealized gains (losses) on investment securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses realized			(2)				(2)
Other than temporary impairment losses realized					(6)				(16)
Other gains (losses)			(26)		5		(24)		(1)
Total before tax			(28)		(1)		(26)		(17)
Income tax (expense) or benefit			7	[2]	0	[3]	7	[4]	6	[3]
Net of tax			(21)		(1)		(19)		(11)
Reclassification Out Of Accumulated Other Comprehensive Income | Pension liability adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Acquisition and operating expenses, actuarial gains (losses)	[5]		(4)		(5)		(8)		(8)
Acquisition and operating expenses, prior service (cost) credit	[5]		0		0		0		0
Income tax (expense) or benefit			1	[2]	2	[3]	3	[4]	3	[3]
Net of tax			$ (3)		$ (3)		$ (5)		$ (5)
[1]	See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018 related to financial instruments.
[2]	Based on 26% blended tax rate
[3]	Based on 35% tax rate
[4]	Based on 27% blended tax rate
[5]	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see Note 12 for additional details)

SHARE-BASED COMPENSATION - Addi

SHARE-BASED COMPENSATION - Additional Information (Detail) - USD ($) shares in Thousands, $ in Millions	1 Months Ended	6 Months Ended
	Feb. 28, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from stock options exercised		$ 31	$ 39
Tax benefit from exercise of stock options		$ 14	$ 20
Long-Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, maximum number of shares issuable		75,000
Share-based compensation arrangement by share-based payment award, maximum number of shares issuable other than options and stock appreciation rights		38,000
Shares available for future grants under the long-term incentive plan		40,400
Long-term incentive plan awards, term (in years)		10 years
Long-term incentive plan awards, vesting period		3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost not yet recognized, restricted stock awards		$ 54
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number, shares		3,497		3,635
Employee service share-based compensation, nonvested awards, compensation cost not yet recognized, period for recognition		1 year 3 months 18 days
Restricted stock awards, grants in period		993
Performance based Vesting Condition | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation cost not yet recognized, restricted stock awards		$ 26
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number, shares		826
Restricted stock awards, grants in period	432

SHARE-BASED COMPENSATION - Stoc

SHARE-BASED COMPENSATION - Stock Options Outstanding and Exercisable (Detail) $ / shares in Units, shares in Thousands, $ in Millions	6 Months Ended
	Jun. 30, 2018USD ($)$ / sharesshares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options Outstanding - Stock Option Shares | shares	6,057
Options Outstanding - Weighted-Average Remaining Term (Yrs)	5 years 4 months 24 days
Options Outstanding - Aggregate Intrinsic Value | $	$ 89
Options Outstanding - Weighted-Average Exercise Price Per Share | $ / shares	$ 28.26
Options Exercisable - Stock Option Shares | shares	4,365
Options Exercisable - Weighted-Average Remaining Term (Yrs.)	4 years 4 months 24 days
Options Exercisable - Aggregate Intrinsic Value | $	$ 71
Options Exercisable - Weighted-Average Exercise Price Per Share | $ / shares	$ 26.77

SHARE-BASED COMPENSATION - Rest

SHARE-BASED COMPENSATION - Restricted Stock Activity (Details) - Restricted Stock shares in Thousands	6 Months Ended
	Jun. 30, 2018$ / sharesshares
Shares
Beginning Balance | shares	3,635
Granted | shares	993
Canceled | shares	(69)
Vested | shares	(1,062)
Ending Balance | shares	3,497
Weighted-Average Grant-Date Fair Value Per Share
Beginning Balance | $ / shares	$ 32.40
Granted | $ / shares	44.10
Cancelled | $ / shares	33.38
Vested | $ / shares	31.69
Ending Balance | $ / shares	$ 35.91

BENEFIT PLANS - Additional Info

BENEFIT PLANS - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amount of years active employees have left to meet rule of 80 in order to be eligible for postretirement medical benefits						5 years
Amount of years left to meet 15 year service requirement for active employees age 55 or older to be eligible for postretirement medical benefits						5 years
Net periodic (benefit) cost, excluding service cost		$ 7,000,000	$ 10,000,000	$ 13,000,000	$ 15,000,000
Defined contribution plan, special contribution, per employee	$ 500
Percentage of matching contributions by the Company to employee's contributions to 401(k) plan	100.00%
Lower Limit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care plan, retirement age and years of service combined years for eligibility (rule of 80)						80 years
Health care plan, retirement age for eligibility, (in years)						55 years
Health care plan, number of years of service for eligibility						15 years
Upper Limit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Percentage of matching contributions by the Company to employee's contributions to 401(k) plan	4.00%
Japan | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions				14,000,000
U.S. | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions				$ 10,000,000

BENEFIT PLANS - Net Periodic (B

BENEFIT PLANS - Net Periodic (Benefit) Cost Included in Acquisition and Operating Expenses (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	1	1	1	1
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	0	0	0	0
Amortization of prior service cost (credit)	0	0	0	0
Net periodic (benefit) cost	1	1	1	1
Japan | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	5	4	10	9
Interest cost	1	2	3	3
Expected return on plan assets	(1)	(1)	(3)	(2)
Amortization of net actuarial loss	0	1	0	1
Amortization of prior service cost (credit)	0	0	0	0
Net periodic (benefit) cost	5	6	10	11
U.S. | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	7	6	14	12
Interest cost	8	8	17	16
Expected return on plan assets	(6)	(5)	(13)	(11)
Amortization of net actuarial loss	4	4	8	7
Amortization of prior service cost (credit)	0	0	0	0
Net periodic (benefit) cost	$ 13	$ 13	$ 26	$ 24

COMMITMENTS AND CONTINGENT LI83

COMMITMENTS AND CONTINGENT LIABILITIES - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Jun. 30, 2018
Commitments And Contingencies Disclosure [Line Items]
Loss contingency accrual, insurance-related assessment, discount rate	4.25%
Loss contingency, discounted amount of insurance-related assessment liability	$ 62
Loss contingency, undiscounted amount of insurance-related assessment liability	94
Loss contingency, insurance-related assessment, discounted amount of premium tax offset	48
Loss contingency, insurance-related assessment, undiscounted amount of premium tax offset	74
Loss contingency, loss in period	$ 14
Loss contingency, discounted amount of insurance-related assessment liability, realization period for associated asset offsets (in years)		4